Can I place my entire 190 lbs on the trunk and fender when working on the engine without damaging something?

Also, a tip is to ensure that you have no metal zippers, buttons etc on your clothing that could scratch the paint when you're doing this.

 

I would not put my entire weight on the quarter panels or the trunk lid, but you can lean on the quarters while working on the engine. I don't think the trunk lid is strong enough to take too much weight before denting. And, the clamshell definitely can't take much weight.

To prevent scratches, first clean the quarter panels (any dirt will scratch the paint, regardless of what you wear). Then, lay a big terrycloth towel on each quarter, to protect the paint from anything you are wearing.

 

If you have a Harbor Freight near you, I recommend that you consider using some of their inexpensive moving blankets to cover the areas you may contact while working on the car.

 

I put a dent on the top of my fender with my knee, trying to reach the ceiling of my trailer with the car in it. So be careful.