I recall seeing a shower curtain upgrade on this site when I was considering various projects. Not sure if that works for you but just search for "shower curtain upgrade" if you think that would solve you issue.

Rich, have a look in the Technical archives (Paid Member access only) to find several ideas for the under-chart table space: wine cellar, an extra cabinet, drawers, tool chest, kitty litter station, etc. [Just kidding about the kitty litter.]

I simply removed the back from the nav station seat to allow the aft cabin door to open fully. That was an easy ten minute job that made the entry to the salon, as well as access to the aft cabin, less constricted. I mounted a rubber bumper to keep the door from banging against the chart table and installed a brass hook to secure the door fully open. A great and easy improvement.

I don't blame you for wanting to keep your C-36. That's how I feel, too, although we would love to go trawler. The cheapest boat to own is the one you already own. (You can quote me on that.) Nevertheless, cheap isn't really the point...the C-36 is just a wonderful boat!
 

I recall a Catalina 42 about ten, maybe 15 years ago (I was then about your age). We departed with me instructing plus two experienced students onboard, and to make a point I had us to go out under full sail and then reef. Winds were in the high 20s and lower 30s. It took us an hour to reef that thing; well, we had a student mistake of a balled up furler line on the drum, but learning was the purpose of the trip after all. The wind instrument captured a max that day of 39 knots true, and the boat was a handful for a while. It was WORK. Anyway we anchored out, then next day wind max was well over 30 knots. My wife and I had been lusting after a Catalina 400, but I called her that night from Friday Harbor and said, "T' hell with the 400! We already own the very best boat for us (especially considering my - ahem - advancing years).

Not once since that day have I regretted keeping our C-36. And I know that like Steve Frost's experience, the day High Flight sells I will indeed have a tear in my eye. 
 

Rich-
Here's a possible bendable shower curtain track option from Sailrite:

http://www.sailrite.com/RECMAR-4108-Bendable-I-Beam-Curtain-Track-Alumin...

Larry/Rich-
I agree about your enthusiasm for the C36 MK II. The in-mast furling, open transom for boarding, classic styling and overall amenities/functional design are really well thought out in this boat. We'd love to do more cruising, but our C 36 is used mostly for family day sailing  and its perfect for that too.

One minor comment about going to a V Berth mattress; it adds another few inches of height vs foam. If you go that way, a small step tool and/or grab handle mounted on the bulkhead will make it easier to climb in.  

Rich, search archives and you'll see two articles I wrote. 
1. Was a shower enclosure with folding shower door
2. A complete cabinet enclosure were chart table chair was
some years ago we almost pulled the trigger on a 42' and then while sitting in it taking stuff apart and looking at storage options we realized we could not put all the stuff we had in our 36 in the 42. Yeah, we did some mods to fit what we wanted but much happier with our 36. 
Chic Lasser
Past Commodore c36ia
​Great Lakes Sales Rep Mack Sails and Rigging