If you go down the detachable bracket route you may wish to consider the dimensions of the board that the motor is mounted on. The black “plastic” mount supplied with the boat seemed too tall at 27cm and it was a struggle to keep the cavitation plate on the motor deep enough. So I made a wooden mount about 21.5cm tall and this seems to suit. The motor sits lower, the cavitation plate is deep enough and the main sheet sheet doesn’t get tangled up with the motor.
I have a smaller 36mm plywood plate too (actually two 18mm plates glued together). I have seen that high plastic plate too but I though it was mounted upside down? Maybe it is intended for a long shaft engine? But now that you mention it I have seen a sawn plastic plate somewhere.
Anyway, like you say, keeping the sheet out is easy with the motor almost touching the transom when tilted, just take the sheet in some while gybing. It is a trick easy learned.
And if it then still wraps around the engine tie some loose bungee cord to the block floating in mid air, atop the bridle. The rubber will pull the sheet slightly forward when it is eased, ensuring the sheet passes in front of the engine.
I have two six inch mooring cleats attached to the front face of the aft bulkhead, just above the benches. (A +S has a MKI aft tank). They not only provide strong mooring and towing points, but they are also perfect fixing locations for the bridle on long cruises. In other words you can also bring the entire main sheet rig forward. The only down side is that you are not allowed to race with such a set-up.