I haven't quite decided yet which direction I will go with the extended range tanks. I have however installed
attachments to the outboard section of the tanks so that I can go the
Hotel Whiskey route or build my own out of fiberglass.
See my Tank attachment fittings here:
The first customer built RV-10 to fly had a fuel capacity of 120 gallons by extending the tank to the entire outboard section. If I can get an extra 10 gallons per side I will be happy.