My Interstate is a twin bed model so the seat you mention isn't there, never was. We like the extra space made available by the absence of this seat. This is one of several reasons we like the twin bed; but that's just our take on things. No matter how you look at it, these rigs have very limited storage space. We have found some ways to make it work for us but I don't know how it will work for a long trip with the two of us and the dog. I may have better information this fall.
2010 Interstate 3500 Twin Bed
(2008 Freightliner CRD Sprinter)
TAC AK-1 !!