Most of the downtown casinos will have at least a few 3:2 games but their rules aren't always the best. I think El Cortez downtown is the only full-pay single-deck game in town. The Sahara, on the North Strip, is supposed to have some low-limit games. It's a decent enough place and has lots of food specials. Ellis Island, a block east of the Strip, has 3-2 and low minimums. It is really hard to find 3-2 games with low minimums.
No need to get yourself backed off before you develop a winning game. As you improve your game you can figure out how to get more money out there. Since you are just practicing I would suggest you use no more than a 1-4 spread, but others may disagree. Casinos have much better security than they once did and are pretty quick to catch this. I would be really careful with trying to backcount.