I totally inverted my Weekender (still not sure how - did the main sheet jam?). All sails set - but the wrong way up! She was quite happy that way, and I climbed up to sit on top of the hull.
I was able to right her using standard dinghy technique, standing on the keel and hanging out off the rub rail (first time, we went right over the top, to lie flat on the side, when I was able to get the main down). Then, with a bit more care, I brought her upright and rolled into the swamped cockpit before she hit vertical.
She was very unstable. I began bailing, then help arrived and I got a tow, rolling a lot, back to dock.
At the time, I had a sealed-off forepeak, and sealed spaces behind the seats. However, the forepeak flooded because somebody (guilty) left the hatch unfastened. I suspect that if she had not had the extra flotation behind the seats (airspace), bailing would have been impossible as she would have had no freeboard.
Since then, I have made the forepeak more watertight, put a flotation bag in the lazarette, and two smaller bags in the lockers under the seats, so there should be flotation fore and aft, which was lacking before. Yes, I think mast-top buoyancy would be very useful - but can I bring myself to have a big blob up there? Perhaps self-inflating buoyancy.
Getting back in was easy, but would not have been if I had been tipped out and she hadn't swamped. I now have a rope stirrup to tie round a stern cleat to give me a foot hold.
I was lucky, it was mild, the water (a reservoir) clean and smooth, not a lot of wind (how did I invert?!). I do not have a lot of experience, and experienced a mildly panicky moment as I discovered myself under the inverted cockpit. Flotation device was marvellous, allowing me to concentrate on righting the craft without having to work at staying afloat.
I left feeling elated - these boats do capsize, but can be righted in the conditions I mention by a single person. But I want to avoid doing it again!