I've been rolling with a 6' pickup truck bed & camper shell for 17 years. It's easier to go diagonal - but not absolutely necessary. I keep speakers up near the cab & rest the neck on that, so I can go straight in and have room for a bunch of PA gear if necessary. I even once had my 3/4 and 4/4 in at the same time! (Not going to start doing the backup bass thing with DB - but I could LOL.)
If you can get your 3/4 in diagonally in the bed of the Ridgeline, slap a camper shell over that and Bob's your uncle.
If you're stuck using the passenger area, all is not lost. I once managed with a loaner 4-door sedan. I wasn't sure it would work, but I managed by scooting the passenger seat all the way forward then putting the back all the way down. That worked out surprisingly well. (Wouldn't want to try it with the 4/4 though.)