That specific set-up seems terribly inconvenient and not very user friendly. Dabbing should be quick and easy - that sounds like a pain in the ass. Perhaps try thinking about making the upgrade to a
Domeless Nail for dabbing?
Titanium Domeless Nails - These seem to be the most popular type of nail. They hold heat very well and are least likely to break.
Ceramic Domeless Nails - These nails heat up and cool the quickest. Easy to clean - just torch it and blow away the ashes
Quartz Domeless Nails - These nails are popular for their sleek appearance and are usually favored
Using
domeless nails for dabbing should eliminate most of the chance for any black residue going straight to your glass.