The tray and clamp seems an ideal set up, though I guess some thought as to what might happen in a collision may be best applied...? In that case how well might the tray be fixed to the bodywork, and whether to mount the clamp relative to direction of travel. The battery on my mid 80`s +8 sits close by the diff with similar clamping arrangement.... Though in the case of a bump to the rear it seems the fuel tank is at risk of being punctured by the handbrake equalising mechanism, with battery damage/location perhaps providing a source of ignition.....Think there is info on GoMoG so related..?