I would really think about other panels. Could be cheaper. Certainly simpler.
The 4 batteries to replace every few years, an expensive DC/DC converter (and it's losses), maybe a charge controller, etc...
It seems like a lot of money and efforet to use a small PV because it happens to already be there. Guessing both together only make 1.3A.
The money saved on 3 extra batteries, converter, battery cables, 48V controller (if needed) would go a long way on another panel.
Plus, the PVs could be sold to someone on the board already using a 48V system. Might get enough to buy a 45W HF kit, when a good coupon is out.
The panel sounds kind of marginal for a 48V system, with 53V at peak power.
That's 13.25V per battery before any voltage drop for wire or a diode.
G-