yes, PVC pipe will work for the fixed spacer. I use 20wt oil in the forks. I pull the springs out, collapse the forks and fill them with oil to within 4" of the top of the fork tube. Re-extend the forks, put the springs in and caps on and you're good to go. If you find that the forks compress to the point where hard parts hit hard parts (ie wheel hits the pipe etc) then add a bit more oil to the fork. You can adjust the fork to the point where it will hydraulically lock before things hit that weren't designed to touch.
TR