You must have been totally exhausted. My knees and back ache thinking about this pack out especially when you start doing the math: 250 total lbs. - 225 lbs of boned out meat and 25 lbs. head/skull. If you took 25 lbs. on the 5 mile return trip to the truck along with your gun and other gear that leaves 75 lbs. / trip for the remaining 3 trips. So you did 35 miles of walking on that pack out and 15 of it with 75 lbs. on your back. That is quite an accomplishment. Don't switch to muleys, just hunt closer to the truck as you get older!57 here.
Absolutely debone. I tend to prefer going a little heavier vs. making more trips. Even an empty trip can have some wear and tear. Not so heavy as to risk injury though. 3 or 4 trips for ~225 lbs of meat, possibly hide and/or antlers. If pass someone on horseback they can be very helpful!
The last bull I packed out, ~5mi each way with one crazy steep climb, made me realize I need to be honest about my knees, distances, and slope. Or just hunt Mule Deer!