It has been quite a few years since I flew Fletchers on Ag work. But from memory the trim was always wound right back for landing, and as you waited for the load to be deposited in the hopper part of the pretake off checks, an extremely brief check, but it did involve winding the trim full forward, just to counter the load. The hopper was quite compact in as far load spread was concerned, very close to the C of G. There was a full bulkhead immediately aft of the cockpit in these versions of the FU24.
How much has the Walter conversion changed the configuration? is that bulkhead still in place? does it still have manual fore and aft trim control?
Would it be possible, with a combination of aft trim for take off, and the heaviest people at the aft end of the jumpers position to put the C of G so far aft as to be uncontrollable??
The pilot had many hours of parachute dropping, but how much of it from Walter powered FU24's?? Would the acceleration at the beginning of the T/Off run be enough to inadvertantly push some of the jumpers to the back of the aircraft? does the Walter conversion have a bulkhead at the back of the fuselage to prevent any weight being placed to far aft?
No doubt all this will be answered when the accident report comes out, but as I suspect, as has already happened to some extent, it will be reactive, rather late now to be proactive.