I had a pass through on my design too but opted out for several reasons, mentioned by SkiFreak, the biggest two are complexity of a rising roof and most important to us was environmental, I went to great effort to have the camper insulated from the elements, 2" of wall insulation and double paned windows, having a big gaping hole would surely screw that up, especially right next to where my wife sleeps. We live in Canada and have been out in -20'C snow and we live in the camper 6 months of the year in Mexico in +30'C heat, the cab is pretty much outside temp in those conditions.
Mine also started with the idea because of a dog. I have never in 10 years of use found I wanted a pass through or felt I needed one but man at the start I was going to have one No Matter What! funny how idea change......