You put your 16k bulldog in a bag and let us know what happens when he gets bored and wants out
banman
We had excactly that problem when we took him kayaking. He decided when we were right in the middle of the canal and about 45 mins from home that he violently objected to the activity and despite the fact he can't swim began to try and launch himself into the canal. 16k of unstable weight in a 1 person kayak was significant. I'll try him out on the 125 to start with and just potter about my neighbour hood to see how he takes to it and what he does when he's bored and take it from there. If he likes it AND behaves himself I'll buy a proper tank box for him.