Powder coating such a large object isnt really budget minded. Ive used POR 15 and havent been happy with the results. Ive had issues with solvent popping, thinned or brushed on. I have started using Eastwoords version (I bought a pint and ive used less than half and half the frame is done) It doesnt require the prep that POR 15 does. Pretty much a Wire brush (by hand) to get the loose off, then a good cleaning to get the dust and dirt off, then its just a matter of brushing, rolling, or spraying on the product.

I havent used Zero Rust, Ill have to check into that for my next project