Hi. Waxing is probably uour best bet with regards to all "butt hair". I wax almost everything below the waist and i really like the results. Try not to be embarassed about the person doing the waxing seeing you, i'm sure they've seen it all, and worse (at least that's what my esthetician tells me!).
Also, you can try a product with salycilic acid made especially for ingrown hairs, I use Tend Skin, but i know there are others on the market. I haven't had an ingrown hair in years.
Good Luck!