Good for you for finding a middle ground and being home with the lov eof your life. I gaurantee you will not regret the choice you have made. I too am a SAHM and love every second of it. We are very very blessed.
With regard to the diapers, I actually think it may be the wipes you are using rather than the diapers. We were using regular sensitive wipes and our daughter had horrible rashes. We were switcing to more healthy eating at the time and recognized something we were using was bad for her. We tried seventh generation wipes and they don't have all the chemicals and additives regular wipes have. Even the sensitive ones have propylene glycol which is what they use in windshield wipe fluid. Same thing that makes it clean it well. How we put that on our babies bottoms is unreal but most people don't know what 1/2 the ingredients inside them are used for or made from. So, I would try the wipes thing first. If that doesn't do it, you should try cloth diapers cause the cotton will not irritate like the plastic diapers are produced from. Honestly I would love to switch to cloth diapers myself but my husband is totally scared of the notion and I have to work with what I have.
Anyways, good luck with your baby's rash. If neither ideas work I'll give you some more ideas that would work.