As others mention, a dew shield would better address the secondary dewing up. I read somewhere that the length of de shield should ideally be the aperture*1.5 (e.g. an 8" scope should have a 12* dew shield extending out).
The great thing with dew shields is that you can easily make a couple of baffles with some black plastic and compass and scissors, and stick the baffles into the dew shield.
Although the baffles will slightly vignette the image a little, they will also give a nice contrast boost, since they reduce stray light getting into the scope; the best way to remedy stray light is to stop it at source after all.
To test this, tray looking up the inside of the scope with the primary removed and to a before and after dew+baffle rings. You'll be quite surprised by the halo glow at the mouth of the dob before, and the darkness after with baffles!
As for wrapping the OTA with some insulating material, that will slow tube cool down to ambient, but more importantly if you view for say 1+hrs, the external insulation will prevent the tube cooling *below* ambient during the night and so prevent tube currents forming.
This will improve your image viewing as the temerature deltas don't interfere with the lightwaves, so a 1/8pv primary can start producing 1/8pv images and not say 1/4pv images.
But by far the best way to insulate a solid tube dob is with 1mm polystyrene roll used to insulate walls in houses (https://www.google.c...olystyrene roll).
Apply contact cement (https://tinyurl.com/5c5bmam) to the polystyerene roll and to the inside of the tube, stick together and then apply flocking over the top.
Doing this will also slow the secondary from dewing, since the sky-side of the upper dob's metal tube won't be supercooling below ambient and dropping cold air plumes onto the secondary as to chill it and hasten dew forming.
More importantly, polystyrene will make the solid tube *thermally inert* which means it vanishes from the view- no impact whatsoever. And with a boundary fan cooling the mirror to ambient and therefore no thermal deltas within the tube, and no body heat plumes at the mouth of the tube thanks to the dew shield...
... You'll get tack sharp images as the highest strehl possible by the mirrors is delivered with no interference from heat or dew.