Am I asking to much from 2x T105's?

How do you recharge the batteries? Solar?

I find that two 6s can run 100a inverter loads down to about 75% SOC (12.4v say) and you need four 6s to be able to do it at 50% SOC. YMMV--there are several variables, but others here have reported something similar.

In my experience, the voltage drop for a 100a load depends on the AH capacity of your battery bank the inverter is on. Higher capacity, less drop.

Once that initial drop occurs, then the battery voltage tapers slowly while the load is running.

So if the initial drop is say 1v, and it will drop another half volt during the run time, you need to start at above 12.5v on that bank to stay above 11v inverter alarm.

The capacity of the bank gets smaller in cold weather and also as state of charge is reduced, so if you are near the edge in summer it might not work in winter.

If your two T-105s are not able to do it at 75% SOC or above:

-they may be sulfated to have less capacity than normal for their SOC
-your inverter-battery wiring is fat enough but there may be a connection issue negating that fat wire advantage.

It would seem like they could put out that much but The batteries are dead at 12 volts or less. Best to stay at 12.40 and above all the time. The batteries may be toast. Im not helping much but I started looking at toasters, hair dryers, microwaves and went with a generator. I use a 300 watt pure sine for my 24 inch led vizio tv's and laptop only.

would 4x T105 (2 in series, 2 in parallel) work?
I'm realizing, that I probably can't add to what I have, so I'll probably start from scratch in choosing a battery.

That's a LOT for two T105's IMO. To keep off the low voltage alarm, you'll have to run the coffee pot and MW at a higher SOC which means you won't be able to run either towards the end of your trip unless you throw in some recharging to get them at a higher SOC before running those devices. It's still hard on those batteries though.