Utilizing sandbags, some steel poles or something, and some cinder blocks (Obviously do not include wood in the process), if you have the room to build it, you can build a temporary oven, and use a propane heater to get the temps up... just has to get to 350-400 depending on your powder, and hold it there for 20 minutes... then cool down... Powder coating is not rocket science. a harbor freight sandblaster ought to do the trick... blow it off and make sure its clean... and then get one of those Eastwood powder guns... Start in the tight areas, coat them well, watch for Faraday effects, and coat it. I'd build a small rollable rack for the chassis, coat it right outside the oven, then roll it in... be sure to use all metal wheels with no plastic or greased bearings
For that much money and time, you could DIY that, and it'd feel that much better than you did and save $$
and then now that you have the powder gun, get a smaller oven for small parts, or just diy that to, using oven parts.
(used to powder coat my own manufactured parts, i'm very familiar with the process)