Before you do that - i'd recommend trying this.I'm currently working out a design for a stock extension, in order to shoulder this properly.
I added a single point sling to the mix - one with elastics so that when you bring the gun up you 'pull' it against the elastic straps.
That actually adds a hell of a lot of stability. I have found the sight picture holds almost as steady as my full stock rossi. It is a great improvement over firing the ranch hand 'free hand'. It just attaches to the saddle ring.
It took me a bit to find the 'right' single point sling - many are designed for much heavier guns and are too stiff, or don't quite fit right with the size of the rossi. Im' currently using a voodoo single point sling (which Gary sells at wanstalls). Cheap and effective.
I would suggest giving that a try - when you wear it if it's sized correctly you can swing the ranch hand to the rear and it just rests on your back and doesn't really go anywhere even if you bend down to pick stuff up. But it's ready for instant use and swings forward smoothly as you bring the gun up. So it doubles as your carry system AND a shot-stabilizer similar to a stock.
You MAY find with the right sights and a little practice that this gives you the extra accuracy you need and also provides a good carry option (under OR over a coat) and then there's no extra 'take down' stuff at all - clip it on to use it, clip it off if you want the ranch hand ''freestyle' or need to put the ranch hand down for a while.
I suspect you'll find once you get used to it that you prefer it over a stock extension. It's kind of like a 'reverse stock' - pushing away to lock up the sight picture instead of pulling towards you so to speak.