In a previous life I pulled a flatbed trailer over the road. If I had a load of pipe, either a few large diameter pipes or many smaller diameter pipe the results were the same. Better fuel mileage if the front of the pipe was covered with a tarp instead of leaving it open for air to flow...
An electronics supply store will sell you 1/16" shrink tube. Clip 1/2" of fuzz off pipe cleaner end down to the wire center and slip a 1" piece of shrink tube about 1/2 way onto pipe cleaner wire end. Heat the shrink tube a bit with match or heat gun and watch it shrink down to small enough...
McMasters-Carr will sell you aviation drill bits that are 6" long pretty cheap. You can get them in #44 and #43. After drilling your axle holes with your carbide bit, slip the butt end of the 6" drill bit into axle hole and use a 6" machinist square against the body to check the drilled holes...
Darn John, sorry to hear about your accident. My prayer is for a speedy recovery for all involved from any injuries, aches, pains and bruises. Everyone feel better soon.
If the tungsten was glued in with epoxy, use a heat gun, carefully, and cubes can be remover rather easily. A utility knife will cut/scrape the epoxy off the cubes pretty easily once it was heated during removal. Takes a little time but worth it.