Thanks again for your suggestions.
There is still sufficiënt space behind de front panel, below the display, above the cooling vent ridge.
If proven a usefull feature I will place that remote box there. The controls switches can then positioned downward and so manual/remote control that (almost invisible) from the frontside.
No soldering needed.
For evaluation its now mounted in the backside, until I feel its a usefull control feature, worth adapting the frontpanel.
(For ir remote, just place a mirror tile behind the unit btw)