Indeed, looking at the tyre sizing chart, it seems that I probably have 20x7.50 rims though I thought the panel had 20x70 written on it. The rims might not be original anyway. Looking again at the chart, there's a surprising degree of tolerance between tyre sizes. It sounds bizarre that I can fit a 9r22.5, 10r22.5 or 11r22.5 on the same set of rims.
The new bathroom vanity top still needs to be painted but its a bit cold to be doing paintwork at the moment. Not just to be outside doing the painting but because the paint just won't dry very well in these temperatures. A look inside the hillbilly cable compartment showed it to have cobwebs. That's not welcome to the international President of the arachnophobes club!
Thinking more toward power options it looks costly whichever way I go. Solar panels are desirable though I'm wondering whether a wind option might be more economical. It would be tiresome to keep erecting and dismantling but would potentially offer more power while maintaining the non motorhome external appearance of my bus due to its removability.