I've been thinking about what connectors are best for this project. After a visit to American Science and Surplus, I've settled on a XLR connector for the T/R switch becuase it offers good shielding and I'm already using them on the motor controllers for my UGV. I'm using 4x RCA connectors for the trigger signal connectors on the Raspberry Pi. (There will be a 3.3v/5v level shifter that will also provide some protection to the Pi.)

Power connectors will be 2.1mm ID / 5.5mm OD barrel connectors.

I'd love to hear any feedback on these choices.