A few modifications I made (yeah, I'm pathetic, I know).
First is Resolute Scarlett. After I got the PoC ninja/commando Snake Eyes, I immediately started thinking about getting a Scarlett to go with him, and the Resolute version seemed like an obvious choice, being a fairly straight-forward update of the character's original appearance, much like v54 Snake Eyes. The head had to go though, and I ended up chopping down the legs as well to make sure she'd be visibly shorter than her partner. Snake Eyes donated a katana and scabbard for some additional visual harmonisation between the two and the finishing touch was the belt from the original 25th Scarlett both to off-set the big empty space around her waist and to give her some spare bolts/quarrels for her crossbow.
Also, can't really count these changes as mods, but gave Snake Eyes a backpack from the RoC version and an MP7 from Beachhead (since a modernised Snake Eyes should really be carrying something a little newer than an Uzi) to emphasise the "modern commando" look:
Together:
Beachhead. Gave him a couple of leftover knives from Resolute Duke figures to fill out both his knife sheathes and the mini-backpack from "Rescue Mission" Snake Eyes, which fits perfectly above his back-knife sheath:
Finally Cover Girl. I rather like the basic RoC figure, but the boots, and, again, the length of her legs didn't sit right with me, so I used a combination of Cover Girl upper legs, Hawk lowers and Shipwreck feet (since they're tiny) to achieve my desired look (didn't even have to do any painting):
