Keep in mind you are limited by a gross weight of 1320. QUOTE]
Correction - if you certify as a LSA, you are limtied to MGTW of 1,320lb. If you want ex-AB, you can go higher. How high? Hmmm.....
TODR
Aside from discussing whether it would be a very good idea to use a gross weight above what the designer recommends...
[Ok, I can't help pointing out the fact that an airplane like the RV-12, designed to as light of an empty weight as it is, is probably structurally designed with that specific gross weight in mind. It then stands to reason that to keep weight down, there is no extra designed in for a builder to willy nilly assume they can just specify a higher gross weight, but I digress]
Certifying at a gross weight higher than 1320 lbs could be possible under experimental amature built, but it may cause a major drop in resale value.
It could never be flown by a sport pilot. Ever. Once an aircraft has been certificated with performance or specs outside of the LSA requirements it can never be recertified as meeting the LSA requirments.