Auto electricians...or anyone else who knows their stuff...please help

Hey
Ive got a styleside hilux and after having dramas with the electrical acessories mounted in the tray (air compressor, small 12v fluro etc) I realised the reaon they did not work properly. They are earthed to the tray which is rubber mounted (I discovered this after putting a jumper lead from the tray to the chassis and everything worked fine). So I made up an earth lead and have bolted it on.

My question is - at the chassis end of the strap it is bolted to one of the bolts thats holds the fuel tank guard on (this was pretty much the only suitable place). Is this an explosion risk being so close to the fuel tank?

I know earth leads dont often spark, but my concern is that if a stick or similar half rips the lead of it may continually break contact causing some small sparks. The tray also now has an auxillary battery which is also earthed to the tray and ultimately to the chassis by the earth lead in question.

any help or suggestions would be great
Cheers