Upper bedroom measurements of 5.0 TA?

[Al Y]

Hi gang. Question for 5.0 TA owners please. I looked at the specs page but am not clear on the upper sleeping area size. We just ordered a new 5.0 and it will be finished without the corner cabinets, so that two twin mattresses fit. I can confirm with them, but wondering if anyone here knows what the overall length is up there? Hoping to put two Twin XL mattresses up there and they are 38 x 80 long. From what I am finding on line it appears the usual queen mattress they fit the 5.0 with is 78.5” long. Thanks.