I don't know what your link is to, but I use 4 5,000 BTU window units in my bus. I stacked them in pairs in WalMart microwave carts, cut holes in the bottoms of the carts and set them over holes cut in the floor with 200 CFM exhaust fans, so they vent through the floor.
My 27' motorhome has a 13,500 BTU unit and it keeps that comfortable, my bus has a lot mor cubic feet, so I thought I'd need more cooling in it.
With the 4 separate units I can mix and match depending on what power I have, they draw about 5 amps each - if on shore power, I can run all four, on the generator 3 and I can even run 1 for a while on batteries/inverter. Didn't seem to make sense to have all that in one unit, where you're sitting on all that cooling power and can't use any of it because you don't have enough power to run all of it.
I wind up with 20,000 btu's when all are running and this kept the bus quite cool today and it was 111 here, two will keep it bearable, but still warm when it's a hundred or so outside.
I got all four units at Lowe's for 86 bucks a pop, so total cost is on par with an RV unit, I didn't have to put any holes in the roof and they weight about 20 pounds a piece - easy to install. Ready built indoor 5000 btu air conditioners were about 500 bucks when I checked and you still have to vent them to the outdoors through a dryer vent - couldn't see spending all that money for simply putting window units in a cabinet.