We love the front living room 379FL (length does concern me though we already have 39'). We have a keystone alpine that has a 12" center support. I thought that was a big deal but The solitude has 10" support. I have read the cross support under basement is also important and is sometimes only 8". I am hoping the company can respond to this as the 386 is 42 foot+ and it would seem bigger support would be better?? Why are you using 10"??