[DK on the road]

Depending on what state you register the Coach in, deletion could be an option. If you are required to have inspections, you will need to make sure its all working as designed. You may be able to ask EPA about your issue. I know that they have offered assistance to truck owners in the form of $'s to restore or repair a system. An example was in CA where along with our California Air Resources Board (CARB) they offered between 60k to 80K to owners of trucks towards the purchase of a new truck if the old truck met some criteria, like fresh engine in the last few years and very few miles annually are expected out of the truck. They offered $'s also to older engines in newer chassis (gliders). They have also given waivers due to very low mileage usage, or special circumstances . 

 All of this may bring attention to yourself and sometimes it easier to ask for forgiveness than permission.

I would want to keep my final decision between me and a new owner of my Coach, if or when I ever sold it. 

My 2 cents.