Firstly, well done for being so honest.
In such a macho past time, it's difficult feeling to find an honest person to help you learn and get advice from.
Bare with me. I have some things to say
The issue is nerves, not your ability or your bike.
That monster is a damn perfect bike to learn on. How lucky you are.
It's safe, reliable, and right in the middle of a power bracket.
The kind of person who told you it wasn't is likely the same type who would suggest you buy 20 bikes, each being 50cc higher than the last, and to start at a 1985 125cc rebel, just because they did.
A larger bike can get away from you a little more, but it's not like you can't crash those smaller bikes. They all go fast. They can all be wheelied.
I installed a throttle tamer. It helps with low down torque control and takes away a tiny amount of twitchiness to the throttle. Anyone can install a throttle tamer, and I recommend it enormously.
Second thing.. The US motorcycle safety course is a huge joke. While it's better than nothing at all, and it's a very good introduction, most courses have absolutely zero to take you from a parking lot situation to out and about on the roads and streets, and that is the main issue. They tend to be the starter course, the test course, and an advanced course.
Nothing from lot to street. I always thought that to be the most insane thing. It's borderline frivolous to hand people a street licence after that.
That gap from lot to street is a freaking mile apart, both in actuality and mentally to overcome. (for some).
You should see what they offer in Canada. You get your own personal trainer who sits on the back, and they take you from scratch to riding around town and on the freeway.. It costs ten times as much, and I'd pay it in a heart beat.
I was exactly the same as you in regards to the bike waiting for me. I learned on a tiny little beaten up night hawk cruiser that could barely shift gears the first time I passed my test..
Cut to ten years later when I'd done nothing with my licence, I took it again and got a 250cc bike that had shitty fuel injection and would surge.. They'd made the test even easier since ten years back..
There I am looking from that situation to my beautiful Ducati monster waiting in my garage that looks to the world like it can flip upside down just by blipping the throttle, and I just couldn't bridge the gap in my mind to imagine riding it.
Question: How are you getting your bike to a parking lot if you aren't driving it? Have you actually ridden it at all yet?
You're right to practice in a parking lot. I did. I got a churches permission, and just spent hours going around in circles. Practicing stops and clutch control. I even bought little flip cones they use on the course to try swerving and slaloms.
The INSTANT.. And I started just like on the course.. back and forth straight lines just to feel the clutch. The instant the bike picked up I could feel it was the same identical feeling to the course bike, just not shitty.
As soon as I started to feel it, I felt like a million dollars and I knew it was just about gaining some time in the seat from that point.
Even doing a huge slow circle on your bike will teach you that it isn't going to flip over and kill you. It's clutch control just like on the crappy course bikes. It just has more in reserve. That doesn't mean you need to use it. The clutch always cuts the power.
Try to resist the urge to grab the brake. Learn to drag your rear brake for control at slower speeds..
While it might not happen, just remember that dropping the bike isn't the end of the world. Lets use the bike, not polish it and be afraid of it.. A few battle scars can be fixed and parts can be replaced, but it's a tool to get you where you want to be.
Eventually pure boredom got the better of me, and I went out on the road from the parking lot. I rode it home, and back to the parking lot again where I'd parked my trailer that carried my bike to the lot
The street is considerably easier that the parking lot. There's more room for everything.
It's just an experience thing. Oh, I remember a big confidence builder..
Counter steering.. I remember them trying to teach this on the course and having it confuse the pants out of everyone there. Mainly because none of us were getting up enough speed to really feel it, and also because there were so many people sharing the space, it was a near constant circle being ridden, not ideal for getting the feel of push steering.
When you're going in a straight line, gently push one side of the bike or the other and feel how the bike leans when you do it. You suddenly realize that it will steer in the direction you push, not the direction you feel the handlebars are going to turn towards.. It always freaks everyone out with an attempt at explanation, but it's instantly obvious when it happens, and you'll never forget it.
The extra steering speed of push steering was a huge confidence builder for me and immediately explained how it works too.. It just wasn't something that could be done while on the course.
And also, read this. I found it helpful..
I really get and feel your issues here. No one is born with this knowledge despite their, at times, animosity to new riders, and it can take a cautious person a little getting used to. I know I still am, but it's a baby step situation. If you gently push yourself you will be amazed how every single step will take you further and further.
You'll look back at that parking lot you use and kind of chuckle to yourself.
Also, seriously, message me with any questions at all. I bet we could both learn some stuff.