Leaking diesel tank inspection hatch

[Cspirit]

I have one of these on the top of my fibreglass diesel fuel tank:

Whale Henderson Watertight Locker- Door | Force 4 Chandlery

I know that it's not suitable for diesel - it came with the boat, fitted from new.....
Anyway, when the tank is full, diesel escapes when the boat moves. Given that I want to move the boat, I need a temporary solution until I can drain the tank and fit a new more suitable hatch. My current thinking is to seal the hatch threads plus all around with CT1. I expect that this will be difficult to remove when (if?) I replace the hatch.

Any thoughts?

Thanks.

 

[Boathook]

I would expect that unless you can decontaminate the area of diesel very few products will seal.

Can you drain some of the fuel into suitable containers so it is less likely to leak ?