I don't think it matters much. Since you're making your own highway pegs, you can customize how they mount and where. You can adapt them to whatever skid plate you like, or modify the skid plate to fit pegs, or some of both.
I didn't have much trouble adapting the Happy Trails bar to my Enduro Guardian skid plate. All I had to do was drill one extra hole in the peg bar, so that there were 2 holes that lined up with existing holes in the skid plate. Then used fender washers (because the holes in the skid plate were pretty big), bolts, and nuts to mount bar to plate. Can post a photo if that's not clear.
Drilling your own mounting holes in whatever skid plate you have is particularly easy when it's aluminum. I believe the Givi skid plate is aluminum, and pretty thin at that, so probably the easiest to modify.
2007 Vee with too many farkles and 50k+ (s)miles