Designing a non-circular radial o-ring seal

I am working on a design that has some pretty tight space restrictions. I’ve got a rectangular plate (with rounded corners, inside R0.12") that needs to seal a housing. The sealing requirements are IP66.

I know that using an o-ring in a weird-shaped groove is common for face seals. However, I don’t see any guidelines when doing a radial seal. I’ve toleranced it the same as if it were a circular seal – about 12% squeeze on the o-ring

My question is – What is going to happen in the corners? Could some weird loading cause the o-ring to be stretched or squished in the corners and seal poorly?

I don’t exactly have space to stretch the dimensions enough to convert it to a pure face seal. Might it work fine as-is? Or can I change the design to mitigate risk? My only thought is to reduce the groove height so that the o-ring is constrained axially as well as radially and just kinda gets squished from both directions. Axial position of the cover plate is not important.