A final update. We got through the week just fine. As I said above, the gradual transition from mostly milk, some Neocate to mostly Neocate, some milk, did the trick. By the end of the week he was drinking 100% Neocate from his bottles. He ate a ton of solid food - way more than prior to the trip - and we're continuing that now that my wife is back in town.
Just wanted to say thanks again for all the help and support. This forum is great - glad to be a part of it.