My question is:
How do I mount the PM42?
Do I need a special housing in order to mount it under table?
It appears to me that mounting it flush against a surface would prevent, or make it extremely difficult, to attach the 44-pin connector.
Digitrax manufactures three devices which have a 44-pin connector.
These are the BDL168 (and its predecessor the BDL16), the SE8C and the PM42 (and its predecessor, the PM4).
These best approach to mounting these devices is to screw the connector directly to the wiring panel board.
Drill mounting holes in the end of the 44-pin connector (Figure below) or mount using the existing holes of the edge pin connector with right angle brackets.