[lil fu fu girl]

IBD is used mainly as a catch-all term for numerous digestive issues that all have similiar symptoms.This could range anywhere from gastroenteritis or colitis to food allergies. IBD in one dog, cannot be related to another dogs issues as they might be completely different. IBD can also be a secondary symptom produced by other systemic illnesses such as liver or kidney disease.
I think what you are doing by maintaining a diet with minimal ingredients containing a complete protein is the best option. Something you might want to try as well, is a probiotic/enzyme blend added into his food. I have tried this on my pup who has gastrointestinal issues and it has worked miracles. The probiotics encourage positive intestinal flora, and the enzymes assist in the breakdown of foods that their own system might be having difficulty with.
As for treats, whatever main protein that you are using in the wellness, say for example lamb: I would buy fresh from the grocery, and slice into thin strips and make leathers out of it. It sounds a lot harder than it is.
(slice thin, place on sprayed cookie sheet and put into 200 degree oven for 1-2 hours, or until they are hard) That way your pup can still have a treat but not stray out of the main protein that he is being fed on a daily basis. I make leathers all the time for my two as I do not usually feed them store bought snacks unless they are AMD's bullies.

Well...that is all I can think of for now...hope that it helps