There are camera specialist photographic companies that will attempt to dismantle lenses and clean mould off them. Given the number of elements in a DSLR lens, a telescope lens is a stroll in the park by comparison. I will ask camera enthusiast friend for a recommendation.
I noticed the inside of my 300mm F/4 starting to smell slightly of damp so went over to forced ventilation – have not had condensation on the mirror since.
One thought, I recall hearing of an SCT user inserting a tube containing packets of silica gel into the focuser (the tube had a wire mesh end so the air from the telescope got to the gel). You could also buy a couple of large packs silica gel from Amazon and put velcro tape on to them and place a fresh one on the inside of the lens cap at the end of every observing night. You then warm the spare up and store in an air tight jar so its ready for use on the next clear night.