Temporary paint

[Zedn]

I would go with Boxheads way.

If you can get the body work roughly ok, you can go over it with a high build primer (it comes in black). Then when you are ready for paint block it flat, smooth out any lows with 2 pack skim putty, another coat of primer and then paint. Thats my plan.

If you go with temp black paint and do not have experience with body work do not attack it with an electric sander as fibreglass is not like metal, you could sand big holes in it.

[Modena]

I was thinking of vinyl wrap too - it seems you can re-wrap it every few years for a color change (if so desired), and do it quite a few times before it got near the cost of a good paint job. Not hard to remove too when you do want to drop big $$$ on proper paint.