<... really want a good alternator and backup ...>
You got THAT right.  What with fuel pumps, injectors, ignition and now
two water pumps, we will need the stoutest electrical system in all
Christendom.
Has anyone inquired of D-C about a dirt simple check valve option on the
pump? ... Jim S.

Yes, absolutely Jim. On the second question I don't think so but it sure seems an obvious needed goodie for parallel flow systems. FWIW Davies Craig claims only 9 amp draw for their pump! This makes it even more amazing that it works. Perhaps they have a exceptionally efficient pump design. It (the D-C pump) does look better than the pumps that

mimic a standard edwp, looking more like a turbocharger scroll.

Bill Jepson