You have a valid point for discussion, and I'd like to contribute to that.

There is a trend, a pattern that exists which has it's roots quite deep in the history of the aero engine, I've touched on this before here. If you take a grass roots functional full size airboat we are lead to the superb vehicles which are the only way to access wetlands in many parts of the world, and if you consider the means of controlling those your almost bound to result in a rear engined craft. Air rudders demand that flow, add the simple practicality of vision and the driver being out of that airflow then rear it has to be.

But, to me almost exclusively to modelling, front engined boats are proven to be the most efficient when it comes to converting thrust to speed, and this predominantly developed in Europe. Tethered airscrew hydroplanes represent the fastest airboats on a thrust to speed ratio basis of any type, including real ones, and has been around since long before practical RC control came into existence. It is a simple fact that in regions where real airboats are used there is a tendency to head towards rear, even when the control method does not use the thrust, i.e. water rudders. As the sheer volume of such boats knocks the specialist European Hydros into a cocked hat in numbers the dominance of rear engines is easy to explain.

Right now, there is a gap of enormous proportions between the effort that's gone into the development of rear engined boats and the specialist minority of airboat's specifically designed to be efficient, but it is going on in certain quarters, resulting in such current beasts as this:



Closer to your thoughts there have been attempts at front engined craft that use thrust to lift the boat by allowing propelled air to get under the hull, effectively a force fed tunnel boat., indeed some are almost working on a Ground Effect principle. But I've not seen reasons why these craft have not come to the fore.

So I guess those those looking for a speed experience to nth degrees use forward engines, but those that like to share in what is a more traditional way will pretty much automatically head to back engines because they enjoy that as part of the real airboat experience, and those folk form the vast majority of airboaters.

It's a hobby, fill your boots, do what gives you the fun and if that be pursuing forward engines and seeing if that can go up a level from where it is then I'm with you, let's do it