You can carry a portable gen in the front cargo bay, but you can't run one there. the exhaust fumes can get up into the trailer and kill you. Same thing if you run it real close to the open cargo door or under an open window. Big no-no.
We keep the Honda 3000 in the truck bed where it stays, and just plug the trailer into that as required.
Next, two 135w panels should cost about $300 not including shipping, and a controller to run 270w (you might see 17 amps, and you need 20% margin over that, so a 20amp controller is too small, so a 30 amper. costs say $50-100. Call it $400 for the whole thing plus something for wires and brackets, make it $500. Labour is whatever it is, no idea.
So that quote of $2,200 for your pair of 135s is way over the top by miles! Run away!