Repeating and agreeing; side mirrors only. If the boat is narrow (as ours was for years), a flag system or just slight weave to adjust. But either way, the only safe way to back a truck is with side mirrors. Otherwise one can't see the danger zones.
So how big is this boat? distance to axle and width play a huge factor in how difficult something is to back. Longer is easier for sure. Backing skills can look pitiful with an air compressor yet same guy can look like a world class pro with a 30' trailer.
Mirrors.... best tool in the drawer for the task at hand.
