Re: Is it capable for watersports?
I did much skiing behind a friend of mine's zodiac with a 35 hp evinrude tiller on it during the early 80's. I don't remember which zodiac model it was, but it had a wooden transom and floor, soft bottom, inflatable keel (mark II?). The owners had 2 heavy duty D-rings installed on the top of the tubes at about the level of the transom. These were done by a zodiac dealer and they used a good sized bit (about 1 1/2" by 8 or 10" or so inches long) piece of rubber the same as the tubes were made of to hold them on. The piece went through the big "D ring", then was glued to the tube. I remember us checking them out, and my friend telling us that the dealer said there was "no way" we would pull them off. I thought it more likely we'd rip the tubes. But it wasn't my boat, so I was happy to go play

. We abused that boat heavily for a few years, always clipping the ski pulley to those rings, and never had a problem.
As for skiing, kids and lightweight teens, on 2 ski's, no problem at all. Deep water starts on a fairly agressive slalom ski were more of a challenge... even relative lightweights (probably ~ 150 lbs) could expect a big drag, but we all could do it. We even skiied double slalom behind it, getting up on 2 and then dropping a ski. For all skiing, you need absolute minimum weight in the boat, and the spotter has to be right up front to help the nose get down, and you absolutely need to have the gas tank fixed to the floor somehow. My friends had a wooden plate with suction cups on the bottom... that kept the driver from getting smacked from the tank when the boat reared up. Overall, it was quick accelerating, so shallow water starts (from the beach) were the preferred method of starting on slalom... just need to judge slack well.
It wasn't our favourite ski boat amonst our little fleet. The lack of mass meant that the pull from a slalom skier had big effects on the boat (could slow you down). On 2 skis, it was OK, there was no wake. Had to be careful not to get too silly with it. It was entirely possible to turn so sharp that you could get going 180 degrees to your skier and either 1) nearly run them over or 2) pull their arms out.
So based on my experience, I'd suggest you ask a dealer about your particular model. Maybe the ring on the tube thing was just a whacky idea from a local dealer, or maybe that's what they'd suggest (??).