Enjoy and let me know if you have questions or modification requests!
Prints with no supports, I recommend printing with ASA, 4 walls and 20-30% infill. Make sure to acetone smooth for a water tight exterior!
BOM
Heltec V4 main board
Solar Panel: a.co/d/0d9FDvgg
Keystone 18650 Holder: https://www.digikey.com/short/nrt9h949
18650 Li-Ion cell
N-Type Antenna to u.FL: https://a.co/d/01u3qqr1
Some Silicone to seal up the screen, USB port and buttons

The keen eyed among you might notice that there is a hole above the USB port for a screw, I put a heat set insert there for now to attach a molded plug for the USB port but I haven't had a chance to do that yet. For now I just stuffed the port with cotton and then sealed over it with silicone. I have a plug modeled but haven't managed to mold it yet, or print it out of TPU.