your existing design is too conservative with overload ratio. You can add 10-20 more panels without clipping noticeably affecting annual production. There are many, many threads in this forum explaining why. SolarEdge Designer would give you specific numbers to support my statement above.

OP here - Sadly this endeavor was a fail for me. Despite having a lot of capacity for additional panels in my existing design, it is hard to find a company that will simply come out to add a small number of additional panels at a reasonable price.

The economics are just not there, since they need to do all the same work as a new system - engineer plans, permits, etc. As a result, there seems to be a minimum number of panels for any add-on system, and the cost per watt is very high if the add-on is small like <10 panels. You would think slapping on 4 more panels on a string + optimizer system would be super easy - but not so.

Lesson learned - always consider overdesigning your system to future-proof to larger electrical needs (especially EVs).

If anyone knows a smaller guy/company in NJ willing to do this let me know!

It's the opposite where I live. They give you a better price per Watt for adding more panels. I'm not sure if they're permitting it though.

Try to call the same place that did the initial system and tell them you just want to add 2 panels, nothing else. If they want to charge you too much, just DIY. Should be pretty easy to add a panel to an existing system