Building Generic Benroy..Questions Before I Get Started.

Hello Everyone,
I have decided to build the Generic Benroy with a few additions and not sure if it will be possible. Here's what I would like to do.
1. Ordered a 5x8 from Redtrailers.com.
2. I would like to not cut 2" off the crossmembers of the trailer and leave stoc length. Here's one question, do I still need to install a wooden crossmember in place?
3. I would like to build the biggest Benroy I can. Can I build the Benroy 10 feet in length on an 8 ft trailer? If so, what would be best placement for the floor?
4. Since I am not cutting my trailer down and leaving stock width, what effect would that have on all width measurements provided in the plans? Will I need to add 2" to all spar lengths and galley cabinetry? I am building mine where the frame will be covered and not building on top of the trailer.
5. Is it true that only Luan plywood is made wide enough to allow for the wider width of the trailer? Where can I get Luan plywood? Home Depot? Lowes?
That's all the questions that come to mind now. Any help much appreciated.
I have decided to build the Generic Benroy with a few additions and not sure if it will be possible. Here's what I would like to do.
1. Ordered a 5x8 from Redtrailers.com.
2. I would like to not cut 2" off the crossmembers of the trailer and leave stoc length. Here's one question, do I still need to install a wooden crossmember in place?
3. I would like to build the biggest Benroy I can. Can I build the Benroy 10 feet in length on an 8 ft trailer? If so, what would be best placement for the floor?
4. Since I am not cutting my trailer down and leaving stock width, what effect would that have on all width measurements provided in the plans? Will I need to add 2" to all spar lengths and galley cabinetry? I am building mine where the frame will be covered and not building on top of the trailer.
5. Is it true that only Luan plywood is made wide enough to allow for the wider width of the trailer? Where can I get Luan plywood? Home Depot? Lowes?
That's all the questions that come to mind now. Any help much appreciated.