My understanding is that if you're not causing a scenario where your toons can act autonomously then it's legal. This generally rules out timers (cast wait 2 sec, cast wait 2 sec, cast) and anything reactive (health bar drops, healer casts heal on them) so yeah you should be fine.

I'm with the Lost Ninja though, I think you'd probably be happier with the tweak ui thing. My fingers were about to fall off with my 5 box until I started using this. With a dual setup I'd suggest putting the bars for the upper screen on the bottom and the bars for the lower screen at the top. That way if you can minimize travel. Also don't forget to check the option in the Interfaces section that puts the loot box under your cursor. I don't know if it's always been there but it's frustrated me for years and I just figured it out a few weeks ago.