Transparent landscape while everything is fully lit?

Hi, I started using UE5 3 weeks ago and I want to know how to do the following:

  • have the landscape semi-transparent so I can see what I am sculpting
  • and the same time keep everything else fully lit

Reason is I am using a big plane object beneeth it to use as a background guide on what to sculpt and where. But when I use a landscape translucent material using opacity it is either 0% transparent or 100% transparent. I have tried many ways but the result is still the same:

  • I tried using a PGN with an alpha channel used as opacity value but result is 100% transparent no matter the value of that alpha channel
  • same PGN with a multiply on the alpha toward the opacity

Is this even possible to do in UE5?

If not, I would have resort create a default landscape texture (the same as my background plane), adjust the UV/tiling to have an exact fit and sculpt from there.