Yes leave it plugged in on any of those brand converters. I am a PowerMax fan, but the other brands also have their own fan clubs :)
For your limited off grid scenario, IMO don't bother with the Trimetric or Victron. You will be back home on shore power before you get any use out of it to justify the cost. A week off-grid is no big deal. Anybody can do that even if all you have is jumper cables to give the batts a goose every so often.
A voltmeter is all you need. Even the idiot lights will do fine. They are just a coarse voltmeter. When you get down to "Fair" and it doesn't bounce back to "Good" after you turn the load off, it is time to recharge some.