DK about solar. It depends on the draw of the CPAP, the size of the panel and the amount of sun.
Your ZAMP port is made for use with panels from ZAMP.
There is a Zamp rep that stops buy the FR forum occasionally. Or you can try contacting him through his member page, Forest River Forums - View Profile: ZampSolar
My problem with solar is that for my CPAP, I want an affirmative answer to will I have power tonight, not a probabilistic with solar. But I don't dry camp much in the desert where the humidifier is absolutely needed. So I get by with the CPAP's rechargeable battery. The humidity in South East Texas
is normally enough without adding additional water to the air. But still there are the occasional winter boondocking trips when it would be nice to have more power.