If you would better describe what those " 10 Watt LED chips " are, it might be easier to figure out just what you are trying to do or work with. Most RV LED modules I have worked with are plug and play....no extra circuitry needed. And arrays of LEDs generally work right off the RV 12VDC supply. I have 35 years as a Sr. Telecomm. Technician yet can't figure out quite what you want or have there.
I would not expect an LM7809 to safely regulate a 10Watt load, if that's any help. Also, what the heck is your " 5 amp 90 volt power supply " supposed to do???
edit. After re-reading the original post it appears you got some non-RV specific LED arrays that work off 10 volts. Given the efforts to work around the 10 volt limitation, wouldn't it just be more cost effective to obtain a couple high Lumen output LEDs that were designed for 12Volt RV use instead of acquiring and building all the necessary power regulation to get around that?
