Sure doing it at night works. On some (all?) Atkinson controllers the green negative solar prewire is connected directly to the negative busbar instead of the controller. On a replacement controller (Victron) you need to connect the green solar prewire directly to the negative terminal on the solar controller. I would also suggest upgrading the wires going to the busbars with 6 gauge wire and adding a 40A breaker on that wire. And while your at it you could install a shut off switch on the solar prewire before the solar controller.
2018 GT27Q, 45 nights 9,860 miles, 600W Solar - Produced 75kWh, PD4655L, 6V Batteries, Champion DualFuel, ProPride&BOSP, 16" tires, 2019 F250 PSD
Sold: 2017 FC25FB, 316 nights 40,150 miles, 400W Solar - Produced 200kWh in 216 days
2013 Casita SD17 89 nights 16,200 miles