I don't claim to be an expert on this topic but a couple of things occur to me based on what I have seen in my trailer with the inner skins all off and from some basic knowledge of electical codes.
1.) The 110 and 12 volt
systems do not seem to be isolated from each other much at all.
2.) The rubber grommets would be just for the purpose of protecting the wire insulation as it goes through a hole in the frame or the inner skin. If your conduit does the same that should be fine.
3.) It seems to me that conduit of any kind is designed to either organize wires, protect them, or protect people and things from them. The reason that there isn't any conduit in the walls now on my unit is probably because the wires are protected sufficiently by the rubber grommets in the only places they really need it and because the aluminum inner and outer skins themselves act as a sort of conduit protecting the wire and the people from the wire.
I guess I said all the above to explain why I think the conduit may be redundant. You are going to have to spend a fair amount of time fishing all your wires through it too. My suggestion would be to not bother and rather just get some good wire ties with an adhesive backing on them to help organize and locate the wires in neat bundles by attaching them to the inside of the outer skin. That is what I intend to do with my wiring before I put the inner skins back on. I found some suitable adhesive backed wire ties the other day at Home Depot.