Look into residential panels. Quite a few are posted on CL or Facebook marketplace locally here. I've had 2 - 320 watt residential panels on my roof ($200 ea. new) for over 8k miles and I'm quite happy with them.
They may need a different charge controller than you have as I'm not familiar with go power. Check your roof for room first as they run larger and need a flat area, and they may require more mounting brackets. I don't believe there is anything special about the go power panels other than the shocking price.
Pick up a residential panel or 2 and a controller and use em' as a portable until your warranty is over, then mount them.