Depends also on how you're launching it and what you're trying to accomplish.

Example--for BT-80 and D21 combo, I'd go at least 3/16 rod if not 1/4" and probably want 4-6 feet of rod, especially if there's some wind.

What sort of capsule are you protecting the eggs with? You mentioned dual, and a D21 tends to really spank them at the thrust spike, so good padding in between them is critical. A lot of duals get DQ'd for eggs bumping into each other and cracking.

If your goal is qualifying, you've probably got a decent rocket though big/heavy. You'll certainly deploy low, won't thermal away, so recovery will be fast and probably secure. If you want to win something (regional, NARAM), you need a much lighter model and a whole lot more chute, plus a good set of hiking boots, as modest winds will probably result in 1/2 mile minimum recovery treks for anything flirting with top-4 times.