you don’t HAVE to reboot one at a time. However, rebooting and disconnecting from power aren’t the exactly same thing. you can reboot just one from software and nothing should break. But the simplest way to restart them after changes are made is to simply power them both off and back on at the same time. i beleive its the full power cycle that creates the weird voltage difference that causes the can bus to fry, not simply “rebooting” which is akin to restarting without powering off a computer.
the easiest way is to wire them first, then power them on at the same time, then configure each one without rebooting or powerering down, then power them both off and back on again at the same time. I’ve done it this way hundreds of times. it works.
I no longer just use a connector and hot glue it on. I use wire with crimped connectors on them without the connector housing, and i solder them to the pins and heat shrink them with 3mm heat shrink. no glue there, just solder and heat shrink. its easy to remove when you want to, and will not remove itself unless a pin breaks.