when i looked where to mount mine, my memory is that it would be a mare to mount in the scuttle area without hacking out gromits or cutting then sealing a hole without chafeing wires.
However as you probably know there is a gromit by the servo of a reasonable size that Kevin, and i, used to run the the switch wires to the cabin by the lights switch.
I dont think you'd get the loom plug through from the engine bay, but you would be able to feed the loom wires through to the engine bay from the cabin leaving the plug in the space by the steering column above the pedals, fiddly but do able if the wires will reach the ecu? Which they may not, but could extend the wires, or see if there is a similar gromit/hole through the bulk head on the pass side, not so much room behind the glove box area though and far more agro to access iirc.
I suppose anythings doable given the space and time to do it. Mines bolted to the wheel arch liner forward of the front wheel. It gets some spray, but thats about it unless i submerge it in a ford or sumat daft. But i'll have more than a wet ecu to worry about if that happens.