All that can be wired with the pots and switch outside of the cavity.

Make a cardboard template up with the holes for the pots and the switch, and wire those first, along with wires long enough to reach the output jack. You should then be able to place the template with the pots attached over the control cavity and run the pickup wires up to the switched pots and wire those in. Remove the cardboard and fit the pots and switch in the cavity.

I forget how large the hole for the output jack is. You may be able to wire the jack itself up with the harness still on the template and push it through the hole, and then attach it to the jack plate when its on the outside of the guitar. Otherwise push the output wires through and solder the jack socket. Make sure the output leads are long enough to give you enough slack to do this, but not so much that you've got lots of extra cable to somehow push back in.

I normally refer to this channel for wiring as I think he does a pretty good job. https://www.youtube.com/c/SixStringSupplies