I thought about a couple of these for when I am running my ST in the garage. Any other suggestions https://www.ductstore.co.uk/acatalog/Semi-rigid_Aluminium_Flexible.html
The rear of my bike sits around two metres as the fumes fly from my door, so I would expect the force and heat to get it done.
Why not put a greenhouse fan or bathroom extractor inside the ducting. Plenty of in pipe solutions on the market. All reasonably priced
Works for me also. Door open and a fan on the ground pointed at the door. Let’s the bike run a little longer as the fan helps cooling
You should. After closing the door again, relight your Little Devil propane heater for 5 mins. Job done. Works for me!
Look on eBay for a portable welding extractor, these start at 8” and shift a lot of air. You can attach flexible ducting to vent to outside.