keep the legs level and supported so they can't sink, and I'd take a punt on using it, if I had one.
the excavation could increase the chance of the poo to the armpit situation BillsGU outlined, I reckon.
I have seen the deluxe model with arm rests - nice, and could easily be adapted to hold continuous stationery and reading matter under the arms, I reckon. Could do the same with your model, AB.