Yup, the engine is under the trailer hitch attachment. Doing any sort of basic engine work would require unhitching the trailer, unbolting the deck, removing the collar, then getting at the engine. Basically, a massive pain in the posterier, something my van gave me on a regular basis.
Also, it would be prone to over heating and would be terribly under powered. Again, pretty much like the one I owned.
It was suggested to me that I should have left the trailer rear axle as a powered one, to which I replied "That's crazy talk, that would be way too complicated and prone to mechanical issues..." and then realised that any good German engineeer would love the opportunity to prove they could make that work. And work it would, as long as it existed in a perfect environment without vibration, dirt, moisture, wear and tear...
So you'd wind up one day doing a tight turn and suddenly a line would kink, and the rear engine would to to full speed, dragging you sideways down the street! Yup, I need to do this van over and incorporate that idea.
Alvis 3.1