Used to have a 14' Achilles. No rack, as I hated all the wasted space (four or six round pegs that fit in square holes means a lot of extra corners.)
To and from the ramp was about the same (except that my buddies usually transported their own gear.) The only caveat is that if I stopped for a meal or something, or stayed in a hotel, all loose stuff got locked up in the truck.
Now, with the 18' RIB (quite a bit wider than the Achilles), I still leave the dive rigs on the deck, but have plans for a couple of racks whenever I get the time to get my buddy to build them.