I'm not sure what you mean by the 'increased trauma' from the angled infusion sets. If you are using good antiseptic technique, they should be no more likely to get infected than a straight set.
When we were having problems with infections on my son (5), he was only letting us put sites in his upper butt. We seemed to have several sites get infected on one side. Our endo told us to completely avoid that side for about a month (leaving us to just rotate around the other butt cheek). She felt it could be a low-level infection on the skin was causing the sites to get irritated and infected.
After about a month of not using that side, we started using it again. I always wipe with both an alcohol wipe and then an IV prep wipe. If we can do site changes after a bath, I think this helps, but doesn't always work out that way schedule wise.
The other thing to consider is if you are having a reaction to the adhesive. Is the whole site getting red and irritated or just the part where the cannula goes in? In my son, it was very clear that it was starting around the cannula.
Good luck, I'm sure it is very frustrating!