I have an 18' pontoon that leaves a pretty much 8'x16' open area, we can dive 4 off of it, but it sets low in the water when outfitted. The 22' deck boat dives 4 very comfortably and a fifth with little restriction. I am building a 21' deck boat into a diving and fishing vessel, like an I/O bass boat with a full windshield for the rough days in KS. The more storage the better, while the more open area the better as well. We setup the gear put it in the water and then don it, just works better with these boats (wife once caught the swinging door on the deck boat with a fin on a back roll, was slightly upset by the time she got loose!). As we age, I am sure a small winch will be added to load the gear as well. The biggest deepest ladder you can put on will never be a regret as far as I can tell.