A whole lot of the obvious. Construction and power generation resources. My plan is to maintain mobility with an ad-hoc trade convoy that can roll in and do small scale infrastructure repair and enhancement. Basically the semi-retirement phase of combat engineers is to move over to the Seabee type units (you can move from combat engineers to Seabees fairly easily since they use the same school as Army and Marines and I have both anyway). Hardly any are in their 30s, most are in their 40s and up. Not unusual to see Seabees on multiple age waivers.

We would probably be going around scavenging solar panels off unused buildings and infrastructure and setting up power generation in the zones that remain populated. Distributed production micro-grids in public areas for common usage. We would produce educational seminars on power rationing and utilization of public power charging resources. For example, battery exchange programs where people gather up and bank charged batteries, recondition batteries, exchange batteries and rebuild lithium ion cell packs from old power tool and computer batteries.

It would be important to build a distributed non-grid power system. That means independent battery charging power stations all over the place and they need to generally be public access. Anybody can walk up to one and charge or battery exchange whatever they carry. Kind of like local tool libraries, but for micro power stations built from scavenged batteries and solar panels. Chances are there would be a shortage of inverters and charge controllers, but charge controllers are fairly simple electronics and not always necessary. We ran a fairly large power generation system at the Diaxris project without charge controllers for a little while but it eventually blew out one of the inverters. We never knew if that was from age or overcharging (it was over 25 years old when it blew). Anyway, running that stuff would keep us busy and valued with any community we come into contact with.