Go with option 4, keep the M3 and Denali and buy an X5M. I see you track your M3, so an M5 wouldn't be a good track car. It's just way too heavy. Let your wife drive the X5M as a daily and ship the Denali up North as beater. The X5M has 6,000 towing capacity and you can put it to better use here in CA.
E92 M3 DCT, Cayenne Turbo S, Ferrari F430 F1
911 Turbo (996), C32 AMG, S2000, (E36) M3, Supra TT, MR2 Turbo