Use of later versions of .net in a photon plugin?

Hello, gentle photon forum readers.

I was hoping someone might provide me the answer to this question. I'm writing an authoritative server plugin that will eventually be hosted on the photon servers. The webhooks 1.2 code comes set up using .Net 4.0. I was wondering if it was possible to use say .Net 4.5. Specifically I was hoping to use the fast vector code that comes in later versions of .Net in the System.Numerics libraries. Any chance that can work? Or do I need my own vector librairies?

Thanks for any tips!
Curt