Hey mate..

Have you looked at the little Tenshock Mini Eco
I got one of these for my young fella and we love it... it is very small, it is self righting when you flip it.. very fast for the size of the thing


I also have a Hobbyking Genesis.. this is an awesome fast boat but does need some upgrades, which are fairly well documented. Mine spun the prop shaft right out..
You need to upgrade the tube, the shaft spring etc.. there is a kit available.. then you can put any motor and run 6S lipo if you got the skills.


Then you have the gassers.. mine is pretty slow compared to the brushless ones, but they sound awesome and there is a huge rooster coming off the back of these big girls.. Mine fits in the boot of my ford falcon easy enough. Runs on lawnmower fuel, so is very cheap to run.