How to store colours in a Material Parameter Collections without an alpha-channel?

I can’t seem to find an option to just store an RGB-colour without a fourth channel. This causes a lot of issues which result to bloat, as I can’t do something as simple as lerping between a 3vector and a collection parameter without masking it first. My materials are starting to have too many of these and I don’t know to do.

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Shortly, you can’t.