Most generally when I travel to navigable rivers it has been most always with the little popup camper and the canoe boat rides atop of the closed camper. Also have a carrying rack for the bike. So when I get to one of my favored sites along a river and set-up camp (which are mostly National Forest facilities), there's most generally a boat launching area either up or down river from the camp site. If Sweetie happens to be along (she's a non-fisher but loves to camp), it's no problem arranging to launch up river or to be picked up down river. However, if alone, I've made do using the bike. If I plan to launch at camp site and fish down stream I'll spot the bike before hand (hauling it down with the truck) at the down river boat landing, chaining it with a padlock to the boat landing sign (or whatever). Then when I float down to the landing I'll ride the bike back to camp, get the truck and go back after the boat.
When launching upriver from the campsite I float back to camp and then ride the bike back up where I parked the truck, load the bike aboard and head back to camp.

All this, hopefully, with a fish dinner at the end of whatever excursion.