Hi @onibala
Not sure if I understand what you want to do.
If you thinking on VPLS maybe instead of IPSec you are talking about MACSec, is this the case?
If you thinking about MACSec in a setup similar to:
CE-1 >> PE << MPLS / SR >> PE << CE-2
Depending on the Platform (ASR9k, NCS55xx, 8000) and version you can setup MACSec between the CEs for Encryption.
About multiple frames, push together into a single one by the PE, thats just not how it works but you can jumbo frames.
Hope that works.
Diego