Possibly a seacan insulated and turned into a sealed room with proper AC,Dehu, etc... I've got a sea can thats turned into a grow room that will handle part of my crop, It's a longer term investment but I think they're great platforms for construction and the interior left intact lends itself to many options and easy cleaning. But yeah, you're likely going to require 30A+ of power if you're cooling 2 x 1k lights, the AC load and whatever pumps,fans etc... As mentioned above go window AC in the RV, you could gut it an run poly everywhere. I WOULD NOT USE THE RV ELECTRICAL SYSTEM. Imo most RV's are built like shit and you're asking for a fire loading it up like that.