Can I beat Enfys Nest in GB II with this Squad?

You need Greedo (or Zam) instead of IG-88 for an extra chance at thermals. Your Dengar also needs gear, because the couple of times I've done it, Bossk and Dengar were the last standing. She can do some damage if she gets her AoE.

Something else to consider: My Dengar has about 40 more speed than yours (which is still not fast by any means). But more speed=more thermals. Dengar's the one who really loads them up.