I dove out of a 20 ft inflatable for years... love them.
We never had anyone to assist us.
Typical method was to hang attachment hooks off the boat for your gear.
Inflate the vest, remove and attach to the hook... make sure it is a very secure attachment.
Then, dip down, swim up (usually pulling on the lines on the top and flop onto the air chambers..turn sideways and you are on the boat.
Remove fins, pull gear into boat.
In several thousand dives, don't every remember anyone who could not do it once they got the timing.
That's the way I do it. Make sure you grip something on the pontoons. Otherwise, watch out for the highly amusing (for your buddies) face plant if your hands slip down the side of the pontoon as you try to "bounce" on board.