Since your Grand Design is going to be well over the 10,000 lb cutoff, the Electric Ground Control TT Automatic 5-Point Travel Trailer Leveling System # LC672136 is not going to work, unfortunately.
Your best option is to put one Ultra-Fab Power Twin II Electric Stabilizer with Dual Motors # UF39-941705 at the front of your trailer and one at the rear. With each of these stabilizers having a 6,000 lb capacity each, you'll be well over your GVWR and won't run into any issues.
These aren't... view full answer...