meahtastic has a local groups section. your area may have one thats not in that list, most of the big US meshes arent. if you're in the US chicago, austin, msp and san fran all seem to have active communities of varying sizes. those websites and discord/signals/whatever will have great resources for meshing in your area. a node for someplace like austin isnt going to have the same design concerns as say minneapolis or toronto.

Quite a few guides for solar nodes on YouTube.

The Comms Channel on YouTube is a good start. However, you might want to consider just running a node off the car battery instead of solar. The node will need very little current and won't bother the battery unless you leave your car parked without running for quite a long time.