I was using the Network Links, but I think I might go with the Reward Maps, they seem like a nice mix between difficulty and experience (It's a cakewalk, and yet I find my Level 104 Link gaining a couple levels pretty quickly)
Phew, good luck with that. I was somewhere above Level 70 with Ganondorf with a 5 Star LV3 and it's still not easy. Remember the Damage requirement for A rank is much more lenient. I've gotten the A and have had just under 10,000 Damage. It took me a few tries, but use the SP Restore potion and try to focus on the two lesser bosses first (pretty sure I did Dodongo, Gohma, then Ganon.