Anyway, how important is a pass-through from the camper to the cab?
REAL IMPORTANT! If you don't have one, you'll want one. If you have one, you'll never give it up.
Some examples....Wyoming, February, near 0 degrees, blowing 45 mph. Gotta pee. Climb through or walk around? Your choice. Moab, March, raining like the devil, just pulled into my campsite. Climb through or walk around? Any long day of traveling, need food and drink? Do you take the time to pull over and get or do you send your partner through the pass-through?
Additionally, in the spring/summer/fall we tend to park the nose of the Fuso towards the rising sun so we get morning heat gain which flows into the house from the cab. Conversely, in the winter we have an insulated curtain that rolls down to separate the cab from the house.
My pass-through is about 24" high and 5' wide, making it easy for my 5'8", 140# wife to pass easily through both ways. But I'm a big lad. While I can use the pass-through, I look like a beached manatee in the process, but it is possible.
Any security concerns about getting up and going if things get dicey are, in my opinion, so rare that they're not worth discussing. But there is something to be said about having a second means of egress from the house if your primary access is blocked, the lock broken, or if a fire prevents you from leaving via the house door.
Again, in my opinion, a pass-through from cab to house is highly important convenience-wise, and moderately important safety-wise. YMMV.