First boat for tall new sailor with dodgy bacK

Hi all, sorry for yet another new boat post...I am completely new to sailing and have just enjoyed doing the level 1 course. Whilst waiting to do the level 2 course next month I am pondering which dinghy to purchase. I am 6’3” and about 70 odd kg, in my late 40’s with a dodgy lower back and knees which grumble after too much kneeling. On this basis I probably shouldn’t be considering a dinghy at all but life is too short and I can’t afford a Bavaria yacht...
I am looking for something which is able to move along nicely but is also comfortable. I think comfort will equate to a high boom and a deep cockpit where my feet are lower than my bum. Also not too heavy for pulling up the slipway. (Pulling a Pico was fine at around 60kg.)
At present I’ve only sailed the Pico which has quite a high boom but not much height between feet and bum when perched on the side decks and felt very cramped.

I was told at the level 1 course that a number of taller sailors at the club sail the Supernova. Is the Supernova likely to be more comfortable, ie have a deeper cockpit and similar or higher boom? (I’m sure its a much better performer but need to make sure it’s comfortable). I originally wondered about a Solo but it was mentioned that the boom is very low and the cockpit isn’t particularly deep. Images of the Solution suggest it has a deep cockpit and reasonable boom height but there doesn’t seem to be any used ones for sail. A shame as it’s a light boat too.

Can anyone recommend any other boats that maybe suitable for my situation? As a total beginner I’ll need something straightforward to sail and which doesn’t break the bank for a first purchase. The club sails on a large reservoir and I think races Solo’s and Aero’s and has a handful of Supernovas amongst other dinghies. Difficult to get close to other folks boats at this time with the Covid situation so I’d be grateful for any guidance anyone can offer.
Many thanks,