Mark,
Why wouldn't you use a relay for those high output devices?? I assume you are using switches for these devices or are you using a thermostat. I use both just in case I don't look at the gauges, or it just doesn't register that it should be on.
Then you just need a length of heavy wire to the device, or am I missing something in the post?? Waytek is one of the best for electrical devices. They make great timer relays.
Bill