welcome to Rib net
I have the same SIB with a 2 stroke Yam 20.
If you wanted to fit wheels, you need these trick ones that bend!
I spent a lot of time around Ullswater growing up.
It is a 10 mph speed limit, if you go significantly faster I am sure you will hear about it, as the lake has a regular steamer service.
Not sure who you could talk to on your VHF there other than the steamers.
The Outward bound school used to run a rescue craft there, but I only remember it being when they were using their boats/kayaks out on the lake.
The water is very deep and very cold, it shelves steeply in a lot of places and towards the Pooley Bridge end, shallows out - I remember a lot of green slime sticking to things at that end of the lake.
The Glenridding steamer car park has a small concrete slip, used by Donald Campbell when launching Bluebird there before he moved it to Coniston.
Think he reached 202 mph, there is a plaque somewhere there.
The weather can change quite quickly, so make sure you carry the right kit for that as it does get cold out on the water and kids will get put off quickly if they are cold and wet.
BUT - the scenery is fanatstic and if the weaether is good you should have great time just pottering about.