http://adventuretrailers.com/acckitchen.html scroll down the page to see:
AT's aluminum propane bracket, sized to fit a 10 lb. propane tank.
Compact and light weight.
(DOT 10 lb cylinder 17.4" H x 8.9" diameter)
10lb Propane Bracket is $124.00
Or one from Helmar that is more affordable. http://www.helmarparts.com/product_p/tb-3.htm
Another choice http://www.suremarineservice.com/001-749.aspx
Powder Coated Aluminum Rail Mount Assembly (Tank not Included) for 6# Aluminum Propane Tank. Comes with Rail Mount Hardware, Rubber Bumpers and Tank Clamp. Use to Store Extra 6# Propane Tanks. Will fit 7/8" to 1" Rails.
Another one from etrailer.com http://www.etrailer.com/Accessories-and-Parts/Stromberg-Carlson/2020-JR.html?feed=npn&gclid=CN6wtPrZ4LECFSI0QgodxiUAQg
Stromberg Carlson Accessories and Parts - 2020-JR
Securely transport propane with a gas rack from Stromberg Carlson. Affix to the wall of your trailer and use only in compliance with city ordinances (check your own). This gas rack holds a single, 20-lb gas bottle for use as needed.
Features:
Transports gasoline safely for use as needed
Holds (1) 20-lb bottle
Made in the USA
1-Year limited warranty
2020-JR Stromberg Carlson Single Bottle LP Gas Rack for 20 lb Bottle