Why would you use the game mechanics to sync between your multi sessions?
I think the tintin forums have scripts or posts that describe how to play multi chars at once. Arctic is not the only mud that allows multi playing. No point in trying to reinvent the wheels when someone has already done it.
I don’t have a solution, but if i was to start, i would just get the tank char setup with enough triggers to survive. And the support char would be the main one i control. Once you get the hang of things, you can start to build a more complex system to issue commands to both char from a third non game session. That way, you will end up having full control of both chars and still be able to play without writing 1000 lines of scripts at the start.
So, being able to set action triggers and save them as you go along is important. Issuing direct commands to the tank from the support is critical too both through the game and through the client session.
Of course, besides the client mechanics, you should also choose how you equip your chars to get the best out of both of them. Having nightvision, anti blind, anti curse, anti silence, fly, det invis, max ac etc on both or one of your char would be critical than dam/hp. You need to be able to issue commands and the tank has to be able see things to execute them.