Hey Bleu,
Honestly, i find that Jackson's ( at least in my experience) thrive in cooler temps. I find that it is easier to overheat and dehydrate them then it is to under-heat them. Most of the literature out there will tell you that 77 degrees F is an ambient temperature- I agree with this; however, i feel that the real issue is keeping your "cooler" ambient temperature isolated from your basking spot. Since my Jackson was a neonate, i have kept him in the coolest room in my house, which is all tile and concrete. I keep him next to the window, which i leave open at night. I live in Northern California, so temperatures can fluctuate, however, his enclosure is consistently at 77 degrees F with a nighttime drop to about 65 degrees F. A basking temperature of 85 degrees is also provided. Given your weather in Oregon is not freezing, i would advise against another white light. I find the main issue with Jackson's (at least based on my own experience) is keeping them from over heating and preventing dehydration. It is vital that you keep the enclosure humid and cool. Frequent misting (about 5 times a day, 3 minutes per misting session) will keep your Jackson's hydrated and stimulate his appetite. This may seem excessive, but if you research their natural environment, you will find that all subspecies of Jackson's are from locals which receive heavy rainfall. In essence, keeping your Jackson's well hydrated and cool is the best way to keep him happy and healthy! Like many have said before, i find that Jackson's are a species of chameleon that is a bit more tricky to acclimate. It might be a couple of days before he decides to kick it into gear and start eating. If you have any questions about how i keep my Jackson's, just pm me. From one Jackson's keeper to another!
Cheers,
-Cala-