Charging at the track

let me get straight to the point, i use my real car battery to charge up my rc lipos at the track and it is killing my gas mileage, i saw other people using big batteries, but on close inspection they were using marine and RV batteries,
I was thinking of doing this, but what type of marine or RV battery?

- how many CCA (cold creaking Amps) should i get?,
-should i get a high end one or cheap?

Because i would like it to last long, also what charger for the boat or rv battery, and how many amps should i be charging it at? is it safe to charge this in my room?

any suggestion would be great, thanks alot.