I had a look as I lowered the dink tonight and there appears to be about 30cm spare between the hulls, so a 3.4 would just fit. A3.6 would be doable but pushing it, maybe slightly in the way to walk around the bow on the starboard steps. The lagoon highfield dinghies are very good and very light. Ours is a 3.1 ultralight at around 50kg, with a 36kg 9.9 2 banger OB it very manageable and easy to pull up on the beach
single handed. It planes at 16kn with 3 humans on board (around 200kg total passenger weight) Personally I'd hesitate to add much more weight, even though a larger dink and OB with console would be pretty cool at times, I'd reserve it for a larger cat such as a l450. Ideal setup would be the highfield with foreword tank/anchor locker and a 15hp
2 stroke yammy.