Yeah, you could do something like:

/target [target=party1target, nodead].....

except on your main. Unfortunately, party1 for the main is not you, it's who you'd think party2 would be, and this messes up the macro. It's not a huge deal as long as you're willing to re-click your mouse on the target after you hit this.

Personally, I'm not a fan of the "target the first guy who's alive" approach, since I like knowing exactly who the main is, not who just happened to be next in the macro/party? order. I go further into that more here if you're interested.