Have you not got a 3 leg puller? Worth the small investment. Also useful for getting the drop arm off the steering box, pulleys off the engine etc.
On my late bay I prise out horn ring, disconnect wire for horn, undo large nut (think it was 19mm) and just pull off steering wheel, think on a prototype bay you need a puller.
Oh would have thought the hot water trick could do it , but have seen another trick with a candle and a fag lighter. Let the lighter flame melt the candle wax and flow around the thread and if lucky it will soak in, leave for a few mins and then try to pull off. Worked on a stuck track rod nut. Good luck
Whatever you do put the nut back on a couple of threads or you'll end up smacking yourself in the face, ask me how I know
NLA VW sell a massive thick washer that you can slot behind the wheel and then use a puller. The washer stops you damaging the wheel. Mine needed an incredible amount of force but it came away in the end, in one piece thanks to the NLA washer.
