Wouldn't it be much easier all the way around to get the inflatable cat and strap a couple dry bags on the tramp? There are no "mini lockers" of any size on the average beach cat...at least here in the US, and the only pockets you will find are already on the tramp. Because of the extreme light weight of the Smartkat, it would be logical to assume it to be less weight sensitive. Also face the facts that if you are going to load down a Tornado like a "Party Barge" its performance is going to suffer considerably.
I have to say I am a bit amazed that the Smartkat has the level of performance shown in the video. The rig looks Mickey Mouse, but the proof is in the pictures.
The Smartkat seems to be made to order for your situation.
Regards,
Bob