After further review, I'm definitely going to go with the Volvo electric pump. I plan to get one coming later today. I will need to either modify the Volvo bracket or fab up a custom part for mounting, and also get a metric M16 to -6 AN adapter, but it should be straightforward to mount and hook up. The wiring is simple, just 3 wires (a 12 ga. to battery positive, another 12 ga. to chassis ground, and a wimpy wire to switched ignition). Done that way, the variable speed of the Volvo pump is in "limp home mode" and runs at a fixed 70%.
There are aftermarket controllers available to change that—one is just a simple manual rheostat knob adjustable from the driver's seat, anything from 0-100%. The other is rather cool, it is automatic based on the speed of the truck, and includes a GPS sensor to determine how much boost to provide. Full boost at low parking lot speeds, to minimal boost on the highway. Sounds cool, but I'm just going to start with the fixed 70% choice, and one of the controllers can always be plugged in later if desired.
I have the rack itself mounted in place. The steering shaft route is fairly clear and shouldn't be too difficult, now that I've eliminated the pump clearance issue. I will need to make a couple of small relief cuts just to ensure good clearance, but nothing major.
