Fuel tank seal around outlet

I'm struggling to seal this properly. It's the rectangular hole around where the outlet for the fuel tank is at the bottom is what I mean. I've tried self-adhesive strips of neoprene but I don't think they'll last very long. Can't seem to find one for sale. What do people use please?

 

VWH used to sell a rather weedy rectangular seal. I used strips of ~5mm thick closed foam neoprene strip, and it worked fine.

 

Thanks Snotty. I thought I was heading along the right lines - maybe another layer will do it. It's about an inch gap along the front edge!

 

Is your tank sitting flat?

 

I think so. Tried it all ways. How big should the gap be?

 

Can’t remember. Might have a pic somwhere.

 

I'll take tank out again to see if I can find why it won't sit down. Where's Barbara Woodhouse when you need her?

 

From memory, it does sit right down and seal. Must do, or road water would fill the tank compartment. The VWH seal was only a weedy thin thing, but did the job (until it fell apart).

 

Here y'go. Not a good pic, but you can see that the tank outlet sits right down in the tank compartment.

 

OK something's not right with mine. Thank you for the pic, I didn't go near it today.