The important thing is to keep the air inside the tube dry. My solution to this problem was to find a metal tube, about 1.5" wide. Take a well washed nylon sock (not new) shake the hell out of it to remove any loose fibres. Drill lots of holes in the tube and place it in the sock. Fill it with silica gel beads (you can buy a huge bag on ebay for a fiver). Pull the sock tight around the tube and seal the top with a cable tie. When the scope is not in use, leave this in the drawtube and close off the drawtube (I just leave my camera inplace).
This has the effect of drying the air inside the tube. It also gets over the problem of the SCT dewing up on the inside of the corrector plate. This sort of dew is much more difficult to remove when it happens.
The thing to keep in mind is when you take the silica tube out while using the scope keep it in an airtight ziplock bag whith most of the sir squeezed out to stop the silica gel getting saturated. You need to recharge the gel every few months. You can dry it out in your oven for a couple of houyrs at 150C but given gel beads arew so cheap I just replace. This method works a treat for my C14.
  