I believe I saw that recommendation about the connectors and gasket somewhere, must have been in your thread. Will get those if mine don't work.
You are completely right about dual mono. I already have two RCA to XLR cables as the one you suggested so I would just connect each receiver output to each amp input and be done with it.
For my first project, I'm going sealed to keep it simple. I know this may limit my LF output level but at least I'm going for two subs. In the future I may decide for a third or completely redo the design to a ported enclosure. There is a build by ack_bk which I'm practically copying for these.
I will also look into the peak limiter function, any suggestions for a sealed enclosure (outer dimensions 21x18x21).
The woofer is a Dual Voice Coil(DVC) which, if I understand correctly, measures 8 Ohms at each pair of posts but since it has two you can wire them in series or parallel for 16 or 4 Ohms respectively. My main doubts in that respect where about pin out for the jack and the amp mode which you already cleared out for me.
Thank you very much for your advice Nephilim1.