It is roughly 48x80.
Just an FYI, the 15K upgrade is only $150 MSRP when buying new... about $100 retail. That is a cheap upgrade now, pretty expensive if you decide to do it later. The BHBE has a slideout, they aren't as well insulated as a non-slide model. I would encourage you to think it over before deciding not to upgrade.
I did the elite package on my 29QBS (included the hide a bed), the thermal, the upgraded AC, aluminum rims (wife's decision) and the cargo receiver hitch. We LOVE our new camper. We've only had it out 3 times so far (it takes a LOT longer with the second kid than it did with just one...). Next month we are gone for 9 days, then another 6 in August. The REAL test comes in February when we hit Florida for 2 weeks!