You can up the temp by putting a few pieces of BBQ charcoal in with the chips. If you use a salt brine this would be safer from a food poisoning viewpoint.

If you "cold smoke" fish it is safer to use a true cure, which cointains sodium nitrite and sodium nitrate. The best and easiest route to do this is by buying Morton's "tender quick". It is nothing more than a salt-sugar- and nitrite/nitrate mix. The added bonus with this is it gives the fish great color, moisture, and is a safer fish to eat with regards to food poisoning.