That reminds me, I still need to put the 2nd door in my 86 C20. The 95% perfect bed I got was a single tank truck and I have duals. So I cut the door mechanism out of the old bed and intend to cut the newly acquired bed and weld the door in. That is an option too.
Propane is out, not cost effective these days, but I often thought of running CNG multifuel. Put a CNG tank on side with the filler in the OE location, and keep one side gasoline. It's about a $5000 conversion. CNG startions are popping up all over here and CNG is running just under half the cost of gasoline and most are claiming same mpg with CNG as gasoline but do admit, seems to lose some power. Who cares about a 5-8% loss in power when what you're trying to accomplish is cheap operating costs. I don't drive mine enough to justify the $5K up front cost. I'd want both incase I was out and about and couldn't get CNG, or when I was towing a trailer of carrying heavy weight and need the power, I'd switch to gasoline for that trip.