Well Josh,
I have read several posts in other sites that start off with a kit from either Rocky Mountain
http://www.rockymountainatvmc.com/vehicleSelectProd.do?prevVehicleType=2&prevMake=4&prevModel=469&keyword=STREET+LEGAL+LIGHTING&vehicleTypeId=2&make=2&model=469&year=1988&navTitle=Electrical&navType=type&webCatId=20&webTypeId=193&prodFamilyId=26724&stockId=&listingId=&uri=%2FproductDetail.do or Baja designs
https://www.bajadesigns.com/NET/C-MCYCLE/MOTORCYCLE+PRODUCTS.
Neither option is cheap.
I did a search on enduro lighting kits and there were several pages of other options available.
I also did a search on "how to make your dirtbike streetlegal" and several pages with lots of info popped up.
The other things to consider are the state laws on what is required.
Several guys have had good luck converting CR500's by getting them registered as "Experimental".
After meeting the legalities of lights, High and low beam & switch, horn, blinker, tailights, brake light & DOT ties.
They made an appointment with the state troopers to get signed off on safety and then on to the DMV for registration.
I think you may also get a better Idea on wheels and tires from the Super-Moto guys as they have (I think) been using different size rims for a greater number of tire options.
The jist of what I read was the loophole for experimental vehicles. that was the key to getting their bike on the street.
Sorry to not to be able to give you any better help, I just never had enough money to undertake a project like this.
You might pm idaho500 and Danger4u as they have dual sported their bikes.
You might also try to another post on "How to make my 500 street legal" in the General forum thread.
Best of luck, you may consider documenting the process for anyone else in the future as I don't recall seeing one around here.
Tuck\o/