@wr420 thanks again, worked like a charm - I was able to get this all working with,
- solar charger controller ($38) https://www.amazon.com/gp/product/B01HCL7LEW
- LiIo 36V battery ($45) http://www.ebay.com/itm/NEW-SAMSUNG-18650-36V-4-4AH-BATTERY-EBIKE-VAPE-POWERWALL-BATTERIES-20-CELLS-BMS-/201895735309?epid=1621923126&hash=item2f01ec700d:g:Mh8AAOSwSypY9Y7d
For charging the battery I used an old laptop power cable and have the solar charger outputting 42V/1.5A. For charging the OW+ it's 58V/3.5A
It does take converting everything to XT60 plugs (you could use bare wire in some places but, eh, XT60 is alright). That means soldering + having the XT60 plugs (~5$).