ERIE TOM - I do something similar here with a couple of those 1800WATT UPS units... Have one for the computer setup and the second one for the Ham Radio setup...
The internal batteries run everything for a good two hours.. Give me plenty of time to shut down down things when the power goes off...
I will be adding a 300AH Battery bank in the bed of my truck to support my emergency radio OPS and be available to use when camping as well. These will go to a two-pin 4-AWG connector on the truck next to the 7-way trailer connector. I'm thinking about adding a 2-cond cable and plug outside my window hookup here to plug into the truck bed batteries from my battery grid here in the radio room... That should add a few more hours to the setup...
I monitor my batteries when being used and when they drop to around 12.0VDC I either go into charge mode or turn them off... Makes for good deep cycle batteries for a long time time doing this... Both these 1800watts UPS units have external battery connectors on them.
Roy Ken