I think the water spray issue is down to the unique design of the Bombards transom, but since its this shaped transom that gives it the performance advantage, we all work round the problem.
Short shaft engines have a 15" shaft as standard but on some of the bigger tiller engines the shaft length can creep up to 17". On a standard transom its not an issue but on the Bombard its can cause some splashing over the back. If you search on here you will see some incredibly well designed and manufactured raised transom solutions, but a simple block of wood works just as well.
My 25hp Yamaha has a 17" shaft
You can see its just a little too long for the transom (the cavitation plate should be level with the bottom of the transom).
Just a block of hardwood, not as good as some others, but does the job for now till I get time to make a better solution.