Your friend might not have been able to drive there but someone else might have in a 4x4. If it was just dumped then there would be no reason to take it far from a road,,,,,,,,, over a hedge would have done
There is no sign of potato dirt or any wear inside
There are no signs of fibreglass stains which would inevitably mark a mould
The two side boards have rebates cut into them as does the left hand end
The central rib is lower than the sides but level with the rebates
The rebates are not painted,,, nor is the edge of the right hand board
On the ground are a couple of painted strips of wood,,,,,, the edges are not painted
I think the "top" was boarded up with strips of wood to completely enclose the two cavities and that idea is reinforced with the way it has all been painted.
The legs suggest it is the correct way up as do the drips of paint inside the hand holds
It is not built strongly enough to be part of a fairground ride
There is no sign of water damage inside of the hand holes so it has not been left out in the rain for very long
The boarded underside contour is puzzling,,,,,, if it is the correct way up then there would be no reason to make that contour unless it is to fit on to something else,,, and if it does then why board all of the contour?
The underside contour nearly matches the top contour,,,,,,,,,,,,,, possibly the structure was used to 'temporally' provide an extension of an existing contour,,, the legs only there to stabilise the structure when it was removed from position
If it was manhandled into position then there would have been no reason to put in hand holes unless the structure fitted snugly on top of another contour
I used to be a diagnostic engineer
I think,,,,,,,,,,,,
,it's,,,,,,,,,
a left hand one of these