Run Macros On Heater Commands

I am starting a new printer build and will be using the Duet for its controller. One thing I was wanting to add was a small indicator panel that shows when the heated bed and hot end are active. I know there are some LEDs on the board indicating this already. I would rather not have to try and mount wires on the board to get to these signals. I have seen where the Duet supports a M code to activate lines on the expansion slot. Would it be possible to add the ability to run a macro when the temperature command is sent to a heater? What I was thinking is there would be an optional macro named HEATERxON.g and HEATERxOFF.g that would be called if the temperature value was over 0. The macro would contain the command to activate the line on the expansion slot.

Would something like this be possible?

Have you seen the PanelDue that's available, it's fairly cheap and can run touch screens between 4.3" and 7" which are also really good value if you import from China via eBay.

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DC42 Kossel 330mm x 2meters
My Thingiverse Creations

Yes, I have seen the panel and was going to have one. But I am wanting a status panel I can glance at from across the room to know what heaters are active. This is to complement the panel, not replace it.

Could you not just wire an LED and 1k resistor (assuming 12v - or 2.2k for 24v IIRC) in parallel to the hot end output or heated bed output. It would probably flicker on and off as it regulates the heat but would indicate when they were on.

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DC42 Kossel 330mm x 2meters
My Thingiverse Creations

I am trying to avoid the flickering. I had a setup like that on another printer and it was very distraction. It would keep catching my attention out of the corner of my eye.

I have a solution to the flicker issue I could use. However, being able to run a macro would be easier and simpler.