The little experience I have from launching and retrieving a boat on a ramp, stems from the way I handled my 740 kg Frøken Sørensen. I made a cradle for her and fitted it with wheels, just good enough for moving slowly inside the flat harbour area.
The boat and cradle summed up to some 850-900kg so first time I was to haul Ms Sørensen up, I wondered if my little Suzuki Jimny would cope, at just 1050kg and with a 1.3litre motor. I needed not have worried. Thanks to the 4WD, and even more, the low-series gear, the car never struggled at all. Moreover, the low gearing let me do all handling of the primitive ‘harbour trailer’ at a nice and slow pace without burning the clutch.
I therefore think that a low-series gear does more than a big engine to make handling on a ramp safe and easy.
Arne
Afterthought: It dawns to me that most cars in the US have automatic gear. I have no idea how good they are at towing at walking speed, so maybe my suggested low-gear series is irrelevant.