I am all behind [lol] front mounted hitches. Reducing distance between steering tires and center of ball multiplies maneuverability by who knows how many times, while decreasing effective overall length of vehicle and trailer. Adding winch fairlead rollers to your hitch arrangement is just plain brilliant. So is use of the Go-Pro.
When still in California, often faced identical set of issues with 31' Scorpion and outboards.
Few [none] of my solutions in the 80's were technology based. My go-to's always seem to come out based on measurement.
1] I measured exact centerline of rear window. Applied very narrow Letra-set strip vertically, 'superimposed' on mirror at height of bow.
2] At distance, with upper deck and bow visible, could easily establish line to coupler, which wasn't visible. After trials, knew when point of bow disappeared, the coupler was three feet away.
3] I'd set 2 small orange blocks, 1 outside door in line with the door jam, connected to other by fishing line of correct length. Then, in backing had reference distance just looking out window straight down door line of jam.
Never over ran the coupler into tailgate, receiver, hit bow, or anything! Good thing about a 2 5/8" ball, finds the coupler if anywhere near close.