Having done what you are thinking about recently myself my take is "Go ahead and do it".
Unless your motor weighs more than your boat it's not going to move anything.
The entire weight of the boat is on the ground and the stands only keep it balanced. If the stands can't move nor can the boat.
Unless you decide to use the boom to swing it out catapult style in order to throw it some distance and it hangs up I doubt you'll have any problem. Your yard guy just wouldn't be getting the money
no wonder he made a face.
My boat is on a cradle
on a flatbed trailer. Granted it's only 25ft and the motor only weighs about 300lbs but still it was easy and not the least bit scarey.
Once again I have to call out the experts who say it can't be done because I just did it. Twice if you count putting it back in again. Four times if you count the last time I had the motor out 4yrs ago. That time I didn't have a chainfall and had to use my boom vang
. That was a bit more difficult but the chainfall makes it a breeze.
Now if you're lifting a couple thousand pounds I'd be a bit more worried.
I'll send you picture of my set up if you feel the need.....................m