I hung tarps in the garage to make a paint-booth of sorts, and applied zinc-chromate primer (rattle-cans from Canadian Tire) to the rudder skeleton and interior surfaces of the skins. It seemed to go on well and came out ok, but I got some runs so next time I'll try to apply less - and possibly shoot additional layers if I don't get full coverage.
I also assembled my new welding cart ($50 at Canadian Tire). I think this will be very handy - much easier that lugging the welder around when I need to use it. At some point I'll probably buy the conversion kit to convert to MIG - but that is for another day.