Now if I was dead set on minimizing weight and getting both flat towed behind the moho, I’d do this.
Short or long bed 2wd half ton, stick shift ( the truck will haul the biggest bike made. Only the weight cops here would tell you a Harley is too heavy for a half ton).
Balance the length of ramp with truck height. Preferably lower the truck, low rider to match your bike, lol. Put a winch in the bed. I’ll drive a dirt bike up a 2x10 board into a 4x4 truck but would not be comfortable with a bike that weighs 4x as much.
Tailgate up or down, don’t matter it will hold the back tire of a motorcycle.
You could get the combo under 6000lbs which is doable for flat towing behind a diesel pusher.
Still would need tow bar, brake setup preferably, lights hooked up etc.