My TT is full solar and I can run my AC for about 3 hours with no solar input before I hit the 50% threshold on my batteries. or about 5 hours give or take during the optimum harveting time frame.
My TT is small 16 foot box 19 foot total length and the AC unit is called a spot ac which means it is a really small compact ac unit it only uses 800 watts when running and is as near as I can calculate (from the metric measurements) about a 4000BTU unit. system is as follows:
240 watt Q cell panels x 2
220 Ah AGM x 2
tristarr MPPT45 charge controller with remote temp etc.
magnum 2012 inverter charger with remote temps etc.
bogart trimetric battery monitor
all wireing is pure copper with sizes calculated for less than 1% voltage drop total.
things that help this work: my solar panels cover 95% of my flat roof and I have 6" of clearance form the roof when they are flat, when the are tilted both panels are on an aluminium frame that moves both at the same time, so no shading, and less heat into the roof to start, camper is white helps reflect heat and all walls are insulated with high r factor foam (european style 4 season camper), I have a fantastic vent that I open with the fan shut off to allow heat to escape up
Now in all honesty I usually run the A/C for an hour upon our return to cool off the interior then I shut it down. But I ran it off of batteries once just for $h(ts and giggles for about 5 hours before It got low enough that I shut it down, as I still needed enough electricity to run the fridges until the next day.
I also carry a 2000w yamaha inverter genset for emergencies that I could run it off of while fuel lasts
total investment was reasonable as I bought the solar panels and batteries used when they were 6 months old from a disaster relief org that used them during the fukushima earthquake the TS45MPPT, the bogart trimetric, and the magnum 2012 were all bought new via amazon but I got good deals on them through careful shopping when they were individually on sale or discounted system design, install and execution were all done by yours truly as a project ot keep me busy on the weekends so besides the savings in labor I was not able to consume my normal capacity in beer there by saving even more money