You could set several T-posts with hand driver just enough to stand, rent an air cooled engine powered driver similar to a log splitter,carry driver in fel bucket while posts are driven.
If you are a tinker/fabricater/welder,how bout this? Obtain a Hydrostatic lawn tractor transaxle,preferiably with frame and if lucky,engine as well. If necessary, a frame can be fabed to mount transaxle and engine on. If original engine isn't available or not worth repairing,a 5 or 6 hp push mower engine should be enough power. Provide slots on frame for fel forks. Replacing bucket with forks work better,give better visability and much stronger than bucket mounted forks. You will find plenty of uses for forks. Offset roller to right or left for improved visability while operating. Don't know why you would need to reverse it while at driver's station but a 1/4tr inch rod will do it. Otherwise a lockable lever at driver's station,cable/string/rope from lever to shifter handle and spring that pull's shifter handle toward slow-neutral when rope is slacked. Reel has to be two piece to alow removing wire roll. Two halves of wheels with bolt centers intact would be easy to build. Lawn tractor wheel might make wire roll too small but a larger reel can be welded to original wheel. I'd try and retain original wheel mount system or try to make reels interchangeable for larger/smaller rolls/other purpose. Tension on wire can be adjusted by raiseing/lowering roller which cause's wire loop from roller to ground to increase/decrease. A little practice watching wire loop will tell you if wire hangs up in brush and you need to stop. Let's paint it! :drink: