Yep thinning more will def make it level better,
But will also make it " hotter " so to speak..
If you have touched up any artwork or used any decals it could possibly lift it.
I learnt this the hard way on my F14 resto posted on here!
Other thing to be careful of is re coat times,
If you don't leave enough time between coats you can trap solvent inbetween and cause issues too.
Obviously the rep should know his products so follow his guidelines.
I wouldn't be afraid to block Back Inbetween coats either the flatter u can get it between coats the better the end result will be.
Just a suggestion but do u know any of the local spray paint/panel shops in the area?
Finish will be sooooo much better if final coat is sprayed..
If u take your materials etc you might get it done for a carton of beer possibly...