Yes, unfortunately...you have to pull the axleshaft to get the drum off.
I'd love nothing more than to switch to disc rear brakes, but have yet to find a reasonable solution for the E-brake (since I'm a 4x4, I can't bolt in a driveshaft parking brake)...I know that some calipers have an E-brake built in, but from what I've heard, it doesn't really do the job. IIRC late '90's E-series vans have disc rear brakes with a baby drum brake inside that serves as a parking brake (Mercedes did the same thing with at least their older cars with 4-wheel disc brakes)...might be something to look further into?
Oh, and those rims on your truck aren't really worth anything...I'd be happy to take them off your hands for you
Seriously, welcome aboard