Ryan - At a functional level, a thermostat is just a switch. The catch here, it seems to me, is that you have a system where you want one valve to open and another valve to close with one switch.
I'm not familar with that Honeywell part number but assume it is similar to the V8043E series that used to be on my system. That valve is normally closed and applying 24 VAC opens the valve. If so, use a switch intended for a light which is controlled by two switches. In one position the switch sends 24 VAC to one zone valve and in the other position the switch sends power to the other zone valve. Of course with this system you're limited to two valves but maybe its no big deal.
Another approach would be a simple multiple switch board which would allow you to control each valve independently. A system with one switch per valve would make control very flexible since you could draw from all tanks.
Hope that helps a little bit.