Take the stock seat, and shave like 2.5" of foam out the cockpit, and about 22mm off the passenger or rear area. The dramatic dip in the seat should change the way she holds on to you, providing more leverage thus keeping from pushing you forward. The small of your back should hold against her instead of your @$$.
...underwear? Compression Shorts is where its at. Like the brazierre to a lady, support decreases the probability of Cancer; Plus You can hide stuff in there. They come in Ducati Red, too.

Or just roll commando. This only works for me because the top of my seat is plush. Yeh don't waste your money on the DP seats. The stock foam is perfectly comfortable when the cover is changed. Go Custom!