That sounds pretty close to what I did, although with a slightly smaller accumulator (just found my notes, it's 5.5 gal, measured at 1.2 gal between cycles). And I used the 4 GPM / 60 PSI version of that Jabsco pump (I used the one meant as a washdown pump, as it doesn't have the internal bypass like the fresh water pump version).
I burned up the pressure switch after a few months and it started sticking, so I put the replacement on a relay. I would have gone for an external pressure switch, but I couldn't find an ignition protected one, and plumbing wise, keeping it out of the engine room would have been a pain. So I used a sealed relay and the stock pressure switch instead. It's been working fine other than occasionally chattering a couple of times right as it reaches shut off pressure (which is what burned up the first pressure switch). The relay contacts seem to tolerate it fine though, and at some point I may get tired of it and swap to an external pressure switch, or build in a slight delay for the relay circuit or something.