Vented fuel cap for C EFI

[MelP250]

My classic EFI C5 500 2020 petrol tank has suffered from the apparantly common issue of a fracured internal Evap pipe. which means pure petrol leaks down into the vap cannister instead of vapour. Having scratched my head and looked at a few options. Buying a new tank seems a price way to go - and without any guanratee that the pipe in new tank would not do the same. Thus today I have bypassed the Evap system. except that i can't leave the evap pipe from the tank to vent fresh air due to the leak of petrol into that pipe so thus have plugged it.
Which leaves me with a potentional build of pressure issue. So does anyone know if the petrol cap off a pre Evap classic (which is presumably vented will filt a 2020 tank or can recommend an alternative item.

 

[Landsurfer74]

Run the evap pipe up beside the headstock so that its exit point is higher than the fuel level.

 

[MelP250]

Thank you @Landsurfer74, I had considered this but had concluded that due to the pipe break inside the tank, fuel would always be in the ubend of the pipe where it exits the tank then starts to climb thus creating a seal and still giving rise to a vacuum being created at the top of the tank.

I did have a minor thought re the fuel cap tho. On inspection the body is solid and does not breath, but I noticed that the chrome top of the cap is held in place with a large circlip. As such there is a small bit of movement, and I wondered if I remove the cap then drill a very fine hole on the top of the plastic and re fit the cap top, would this give me surficient space for vapor to leak or air to get in behind the circlip and chrome cap edge to give me a vent to combat the pressure/vaccum ?
Has anyone does this and if so what size hole or series of holes would one drill?