We bought a fishing tritoon this spring. Hubby has owned smaller fishing boats in the past & has years of experience hauling/backing trailers. Me - not so much. Our goal is for me to be comfortable enough to drive/unload/load the boat and he will be the one to back the truck/trailer. For now, I hold the boat at the dock while he gets/parks the truck/trailer. He's gone out once by himself and was slightly surprised it was easier to manage by himself than he thought it would be.
One thing we also decided to do was take the MN Boating course, even though it wasn't required.
In our case this is what happens:
We get in rigging line, undo transom straps, loosen bow strap for about 1' of slack.
I back down until fenders are submerged. I get out and get into boat, wife then gets into truck. I back boat off and she goes and parks truck/trailer. I come back and she'll hop off dock into boat.
When we're done, she drops me off at dock, I back truck and trailer down and she loads boat. She stays in it, trims up, while I hook up bow strap. I pull up to rigging area, she deals with the inside, I deal with the outside.
Perfect method for us.