You won't be able to use Entrenchment mods with diplomacy, but you can still run Entrenchment as normal with it. So if you get bored testing the diplomacy stuff you can just go back to Entrenchment again.

Worst case, archive your Sins and Entrenchment installs so you can uninstall Diplomacy and quickly reinstall the other two if necessary without having to download anything.

It was necessary for me to fix minidumps from enabling/disabling mods.  I was mainly recommending, not because I think it will be likely to occur, but because it's so very helpful should something go wrong.  Restoring the compressed archives takes me mere minutes compared with re-downloading all of Sins and Entrenchment.