UT 276 has a ton of boat trailer traffic - it will be fine for a truck/5er.
I would be very cautious about using the ferry. It seems like it is down more than it is running.
The other option would be to come down through Hanksville, and on to Bullfrog bypassing the ferry.
If you are coming in at night, make sure you slow down south of Hanksville - it is open range, and there are roaming black cows that like to hang out on the highway. You won't see them until it is too late.
We go to Powell 5 or 6 times per year. My favorite place.
2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010