To change one's life: Start immediately. Do it flamboyantly. No exceptions.
I got the rubber gloves out of storage and had a go at the old fibre-glass patching. After leaving the cab floor to dry and set completely I gave it a bit of hard work with a piece of sandpaper and then dusted off nicely. I have worked once with fibre-glass* before and spent three days itching, stinging and scratching. The tiny little fibres of glass pierce the skin and then stay there, invisible and very irritating. Hence the protective rubber gloves :)
It's pretty easy really, cut pieces of the glass-fibre mat to the required size. Then just add a few drops of catalyst to some of the gooey, translucent resin and stir it up to activate a chemical reaction. This allows the resin to "go off" and set really hard. Too much catalyst and it sets within minutes, too little and it takes days, or never sets at all. I was overcautious and added only half the recommended amount as I wanted plenty of time for my old fingers to work with it. As a result it took over a day to set properly but looks great.
* I believe it's properly called GRP, or Glass Reinforced Plastic
I gave it a quick coat of red oxide primer just to keep the whole area protected and stop any moisture from getting to the recently treated metal areas. I made eight separate patches for all of the different rust-holes that I found in the floor. The largest one behind the accelerator pedal got a double patch - the two layers of matting and the resin combined have made a patch strong enough to support my weight! It's not very well hidden but I'm planning to rubberise and also carpet this area so it's not too important from an aesthetic point of view.
Thanks for stopping by