U-bolts or eye-bolts and bridle have been good for us. With a Suzuki 20hp on 3.5/3.8m inflatable able to pull young adults on wakeboard, kneeboard or ringos. Try and position towing points high and wide on transom for better towing, and a bridle with a floating pulley is good for keeping lines clear of prop. Have fun.
Edit: 325lbs is a massive transom weight limit on a 3.6m sib! The transoms on our boats were only rated at 55kg (121lbs) and 72kg (159lbs) respectively. Never pulled one off though.[emoji106]