Poly tanks of every shape and size are cheap.
The IBC tote is probably a good idea, @ 275 gallons it's going to weigh over 2000 pounds full so you're not going to just drag it out of your pickup and move it around.
You also aren't going to want to store a lot of water for a extended time.
Alage grows and bacteria can be your demon.
I'd chlorinate every time I filled up. Read up on doing so, it doesn't take much, do it exactly to measure.
If you had two tanks, used one for hauling and elevate the other you could just fill your RV holding tank as needed from gravity pressure.
About 15 to 20 feet of elevation could give you around 10 PSI.
You could chlorinate in the tank you haul, let it set 24hrs and then pump it up into your storage tank.
It will aerate as you pump which will help dissipate the clorine taste/oder.
Pumping the freshly chlorinated water will also help keep the hoses and pump you use clean and sanitary.