Best way to go is to cut out all bread- even gluten free bread. The truth of the matter is all starches (Atleast most that aren't vegetable) are high gi and will cause insulin spikes---acne. Especially if you're insulin/carb sensitive. You'll just have to prepare salads with lots of protein. Nuts- chicken- cranberries etc. much healthier and just as easy to make as a sandwich. You probably don't like my response becausee sandwiches taste good but if you're serious about curing acne this is truly the only way to go

I have read that sourdough bread can be tolerated more so than other breads.

If you decide to get rid of gluten altogether, there are some alternatives. I would make sandwich wraps out of nori (seaweed). It was rather messy. Lately, for lunches on the go, I just boil some eggs with an apple and veggies as sides. Sometimes I use corn tortillas for sandwiches with a sweet potato (or avocado) spread I make ahead of time. They have a rather low GI but, then again, they are made out of corn, which can be inflammatory. There are also these sandwich wraps called sandwich petals, which are low GI, gluten-free, soy-free, yadda yadda. Delicious but expensive.