A higher handlebar stance helps with side hilling wide or heavy sleds. More leverage. Consider a taller riser??? I increased to 10" riser on my Summit 1000 and made a big difference and am considering increasing 2 more inches. Gotta consider your height and strength also. Taller not always better.
You can also try a ski with a removable saddle. I use Simmons and made some SS plates that move each ski in 3/4" in. This is on my XP. cost me $125 to have the plates made to spec. They are about 1/8" thick and have studs welded on top and holes for the original bolts to hold the plastic ski. 1.5 seasons on them now.