Instead, I acquired two large 140W panels that had been removed from an old installation for the princely sum of $20 (USD).
After struggling with trying to find connectors that I could pair with the MC3 connectors (remember, these panels came off an old installation), I bought a dozen MC4 and just cut off the old MC3 connectors...MC4 is the way to go these days.
Next came the surprise at finding out about "MPPT" - in all my years looking at solar panels on roofs, I never knew they were so finicky about voltage vs current curves...real MPPT charge controllers start at $70 for a Victron 15Amp and I decided to try my luck with Chinese sellers on AliExpress...turns out the charger was a PWM fake sold as a MPPT charge controller.
Anyway, I also needed a battery since the charger doesn't work without a battery source. That's another saga but short story - I built my own 3S battery pack out of 18650s.