Good news that it all went well.
"We only needed to charge every 3 days or so, and I seldom went much below 80% - never below 75%. We're not heavy users of power"
I guess not! You were operating in the 80-99% SOC range where gen time is longest for replacing used AH. this is normally solar people's country.
If you did 50-90s to get short gen times for max AH replacement, it might be once a week or so instead of every three days, hard to say.
Big thing is doing 50-90s with no solar, you get "progressive capacity loss" from repeated incomplete recharges, and eventually your
battery bank has too few AH to get you by even one day. Then you are really stuck until you can get shore power and do a bunch of desulfation routines over a few days before you can go camping again.
Reported my woes trying that in summer 2010. Last year with some solar added and now this year too, no more problems. Doesn't mean run on solar only. Just stretches out the time between gen recharges so the progressive doesn't make much progress. Also the solar keeps you over 90% part of the time which helps by not being so "incomplete" on the recharge as when stopping at 90.
The Vector tapers once battery voltage reaches 14v, so it will taper first when combined with a higher voltage charger, but while it is still running it should add some amps to what your mod-9280 is making.
If you run the Vector with that PD at 14.4, I think you will see the PD drop out first. BTW if the Vector won't even run with the PD already on, the drill is to turn off the converter, get the Vector running, and then turn on the converter and they will both be running (unless you pop the generator's circuit breaker :) )