Basically, my little (808) RX3 is so light and handles so well that now I have a problem lol

With the stock fuel tank,..when driving aggresively. The fuel seams to make its way back up & out the gas cap. There is a relief pressure line there to I beleive.

Ive tried different brands of fuel caps and nothing can stop it from coming back up and leaking along side the new paint around the fuel door ; [

A cheap way to solve this problem so Ive been told , is to cut out my stock fuel tank and insert that racing fuel cell foam? But I worry this may interfere with the fuel level sensor unit thingy.

Probely best just to remove the stock unit and cut out where the spare tire mounts & insert (lower-in) an ATL Racing Cell?

Probley as well I could have a bigger tank , get more range and re-locating to this area would provide slightly better weight distribution. The 808 tank is so dam small anyhow that I have to carry a gerry can at all times!!

Anyone done this modification in an old school RX3 before?