Kudos for contributing to the public good!
I bought this Solar Radio Node, ready made, on Etsy. Not the cheapest solution, but it was still pretty reasonable and it works beautifully. It has now been running out in the weather (in Wisconsin) for more than six months without any downtime and with absolutely no maintenance. Rain, snow, and 40 mph winds have not bothered it any.
You can still connect to a repeater from your phone via Bluetooth. It is possible to designate something as an "Infrastructure Node", which most keeps people from sending direct messages to it. If you do not designate it that way, which really doesn't have a downside, you will be able to use it as a regular node, in addition to having it act as a general-purpose repeater.