Not mentioned is ISTR the OP has a special 12v situation for running 12v inverters at all. The rig's 12v all comes from the DC-Dc power supply gizmo off his 24v system including battery bank, so the question there is how much can it do before being overwhelmed by loads? EG, a rig might normally have a "55amp" Dc converter or a battery bank that can do 55 amps (or more) to run the rig including the inverter(s)
The OP's set-up or the now famous Niner/mena/Mex power supply used that way must have some limits for how may amps it can run at a time.
So how much of a load could the OP do on any inverter he uses from that 12v power supply?
Makes sense to use a separate inverter off battery when on shore power if you have those reboot issues with your regular inverter's transfer switch delays.