Yup Elcaro ..it doesn't matter what idea we come up with.. someone will have done it already
Ok not a T30 but I made my 2.75 Frib into a little motor sailor
Why wouldn't you want stays ?
The mast will take a fair bit of pressure even in a breeze never mind a blow. I use three stays ..same as many a dingy. Its thin dynema rope stays .. as its very strong..so no chance of my mast blowing down.
I bought a sail for a Laser dingy and cut the top off to make the main and jib. Reason being I didn't want it to capsize in strong winds and it would be murder righting a SIB if it capsizes. I have been in force 4 winds in this setup and it was not healing over far due to the short height of sail
You need a rudder of some sort ..so I use an oar fixed to the transom to steer and it works ok.
If you only want to sail downwind you don't need a keel..centreboard or if using a SIB..a leaboard ..but if you want to sail into or across the wind you will need a leaboard of sorts for a SIB. You can see mine in the side on photo..it obviously has to rise and lower to come ashore etc. I can head 45% into wind on mine which is ok for a SIB /Frib.
If heading direct into wind..I wrap the sail up and use the wee outboard..just like real motor sailers do.
So yup..its all been done before..and its good fun both designing the boat so it works and then using it :-D