Tufnol is a composite material so I would say yes you can. There are many different types of Tufnol. Whale, Carp, Kite, 6F/45 etc. They all have their own applications. Any of the above would be suitable for something as simple as a rudder tube.
Just a thought. Who would be responsible for having all the measuring equipment calibrated? Will the MYA have a budget set aside to each and every measurer in order to have their equipment calibrated? This should be done yearly. By a calibration company. Certified. Dated. Signed off. Date of next calibration too. Or will they have to do this themselves? At their cost? I wonder how big the que will be for that! Because if a sail is 1 micron too big, (about a thousandth of a human hair) it is not legal. What will the tolerances be? plus or minus a millimeter? I could perhaps understand if we were flying comercial aircraft. But radio controlled yachts? Stupid.