First question is:
Are both units blowing good COLD air all the time or are they cycling on and off with just circulating the air sometimes ?
One or both units may not be operating properly.....or a vent is blowing directly on a thermostat.
Assuming that is not the case, heat gain through single pane glass is HUGE if in the direct sun. The big awning should help a lot on one side.
I'm planning to find a company that does thermal tinting on house windows to do my RV. I might change my mind when I find out the cost. The really good stuff that actually blocks the IR without being too dark is expensive.
Oh, and I learned the hard way that portable AC units with a single hose are basically a joke. That single hose exhausts a LOT of air.....that has to be replaced into the structure from somewhere. That air is hot outside air that is sucked in through cracks and crevices. You are basically cooling one small area of the house (or RV) at the expense of other areas and the net temperature change for the whole structure might be higher instead of lower.
Portable AC units can be really good.....IF they come equipped with TWO hoses so they work like a real AC unit. Alas, those are a good bit more expensive.