You can also rent in Mennagio. You don’t need a boaters’ license for up to 7 people which is why you will need two boats for 8 people. But you do need a drivers license as I recall so make sure you take two.
We were going to rent in 2021 when we went in August. My son who was going to be driver wanted to wait until we got there. By the time we decided, there was nothing available. We ended up renting at Lake Garda when we made a day trip from Verona later in our trip. It was great fun and would recommend highly. None of us own boats but he had driven a rental boat in the Florida golf a few times.
So it is a bit risky to wait till you are there I think. But there was availability still just before we left which means you have some idea about the weather which is advantage of waiting.