welcome! if you are talking about the 2 part epoxy I think called "glaze coat", i dont see how it will possibly work. even with a really thin coat, it will want to run and drip. you couldnt hang the guitar, i would not think. doing it in several stages i would not think would be easy or good.
you should be able to get a good result at least with automotive lacquer in spray cans, i have. i would think the poly will work too. you just need to wet sand, sometimes between coats, mostly at the end, then buff and polish. should look spectacular and not hard