I was at Mt. Nebo 11/3/07 when this picture was taken:
As you can see, the colors were just starting to change, and this is what I based the trip on. However, I hadn't planned on the weather being so wet down there as it has been. So, you may be right in that the leaves will be gone. Temps, again, basing on average temps for the area of highs in the mid to upper 50's and low's in the low 40's. If you dress in layers, and buy this from Summit for the better half -
http://www.summitracing.com/parts/MXI-20013/ - you should be ok. PM me if you want to know where we are staying. We will be cruising Friday 8am to 4:30pm from Harrison, Eureka Springs, Ozark, Mt. Magazine and back. On Saturday, we will be headed East out of Harrison with stops in Mt. View and others along that route.