I don't "get" SUPs. (But I admit I haven't tried one.)

I think it depends on your priorities. You certainly can't take all your stuff on a boat unless you've got quite a large one. Things like SUP, kayaks, dinghy/motor, bikes, surf/sail/kiteboard, etc. all compete for space and load capacity. As you noted, anything stowed on deck can become a problem in rough conditions.

Don't know how good the inflatable SUPs are, but I think anything on deck that you can stow below or leave behind puts you ahead of the game.