They can build them that size, but then they need to be wider and/or longer, so they can be SHORTER, and thus be homeported in Baltimore & Tampa. (where the restriction is height)
I, too, was on a B2B, and had the cabins next door to each other. After I explained the situation to the people in the cabin next to mine on Cruise #1 (and the cabins were identical in every possible way), they were happy to switch.
We just went down to GS together and it was taken care of in a few minutes.
Nonalcoholic beverages (12 containers; no more than 17 oz/half liter each; must be carried on) ARE permitted. RC's IT department just hasn't gotten around after (what? three years?) to changing that paragraph in the cruise documents.
BTW, "breezing through security" is not dependent on how much stuff YOU have. It matters how many people are in front of you, and how much stuff THEY have. 😉