Hi,
As you know Winni is a really big lake. That, in combination with all of the idiots in their 40' power boats racing around in the Broads can cause for really rough conditions that frankly you just want to avoid in a true ski boat. So just stay in the calmer regions of the lake and be smart about it and you will be ok.
As for the ski nautique that pulled the handle out of your hands - the boat has the power to do so, but a good driver will throttle up properly to pull you up without taking your arms out of their sockets!
My friend bought an 86 Mastercraft that works really well for skiing. It's not my 2006 SN, but we run the course all the time with it. He retrofitted it to have PerfectPass Stargazer GPS based speed control - which is really handy. Of interest, his older MC hull does cut through rollers more easily that my newer SN.
My first boat was a v drive (engine in the rear) super sport nautique, which handled the waves better, had open seating (ski pylon is behind the rear seat) but as the poster above points out was not great for slalom as the wake will be monstrous in comparison.
As for the tow vehicle, will you be able to tow a 80's vintage ski boat, yes as they should be under the max tow rating of your vehicle. BUT... anytime you tow at the max your going to kick the crap out of the tow rig. Also, the Jeep has a very short wheel base, so if you need to make abrupt maneuvers to avoid an accident - I worry you could jack knife your rig and lose control. Another point of concern is the trailers that come with that vintage boat might not have brakes, or if they do they probably don't work anymore - which again is back on the point of the wear & tear this will put on your jeep.
Hope this helps.