Yes the problem is the ECU under 4000 rpm will only give the warmers 10% no matter what the setting, this was veified with a osciliscope. Once the warmers get full consistant voltage they work good. The box you speak of; I had one last year and it works perfect and does not add any load to the ECU and pull power directly from teh battery at the flip of the factory switch. The beauty of the box is that it works with all factory switches and its so clean. Any other solution and your going to lose the control of the handwarmers on the display and you will get a error code flashing because the ECU cannot locate them.
You call it over priced because your are under-educated on how these warmers work! Wiring to a headlight are you serious? This will give you a error code, they will get hotter then haties and then blow the fuse.
Do it right go with the box, or do it wrong and wire them in parallel 06 apex bars with a 07 wire harness and you cant touch the bars any thing over 2 bars on the display puts less then a 1 ohm load on the circuit but so far hasn't caused a problem in any ones sled that have done this.