Here's a few ideas, though the last two items look a bit pricey:
□ Honeywell Remote Bulb Thermostat (Part # T675A1565) - Suitable for applications requiring temperature control of air or liquids where controller must be placed outside the sensing area.
□ Honeywell T775A/B/M Series 2000 Electronic Stand-Alone Controllers - remote sensing of temperature and provides switched and/or proportional outputs to various types of loads. Would need relays to control heater.
□ Honeywell Aube Telephone Controller (CT241-01) - controller has several relay outputs (dry contact). Each output operates independently. It connects directly to existing phone lines and is password protected. Need relays again to control heater.
Anything else you know of?