Hadn't seen those rules, interesting.
Anyway, since you are using and existing WS plane, minimal changes, I assume you aren't going to take advantage of the larger wing span, or changing the chord as long as you meet the rules.
First, last, and always, weight. The min weight is much lighter than WS, and weight is even more important than a powered plane, so you desperately need to lose weight. Either trash your current motor stick, or cut it down as small as you dare, thickness wise. Keep the nose long for balance. Obviously throw away the prop, prop hanger, and tail hook. You can probably sand down other wood sizes too. Stresses on gliders are much lower than WS planes.
Next, rebalance to best glide cg (should be close to your WS cg, maybe a little aft). You want to do this by moving your wing unless you are under the min weight, then add ballast. DON'T add weight if above minimum already unless you have NO choice.
You'll still need to keep your plane trimmed for a circle, which way is less important with no prop, but unless you want to hit walls you'll need to circle.
Now, trick is where to locate and how to design the hook. I don't have much experience here, but there is a community that does. Get on the internet and look up F1A gliders. These are outdoor competition free flight, but I strongly suspect they locate their hooks with respect to the aircraft's cg for a GOOD reason. They also have lots of experience on hook design and tow techniques. Look up something called circle tow.
Hope that helps,