When i got my T/C two years ago I did some calculations and came up with 11 1/2 feet. I posted label on my rear view mirror to remind me and on my first trip back from N Y my GPS indicated I should go under a R/R bridge. I don't know if i would have noticed the bridge was over a foot too low but i AM glad I had a reminder on my mirror.
I AM in F L picking up a 5th and before I leave I AM having it measured and am posting a note on my reViews mirror
2010 Dodge 409 CI diesel long bed dually crew cab B&W hitch, 95 Gallon Auxiliary Transfer Fuel Tank, pulling a 33 foot Holiday Rambler Alumascape suite, Winegard SK-3005 TRAV'LER , Central vac, Splendide 2100 XC washer dryer, Rotochoks, TST Tire monitor.
A few things to remember when measuring: insure the trailer is absolutely level and on level ground if you are going to use a level attached to the 2x4. If there is any kind of slanted pavement, you could be off by several inches either way. Also, attaching the trailer to the tow vehicle is more accurate than simply leveling the trailer front to back.
2011 Ford F350 Dually
2011 Mobile Suites 36TKSB3
Reese 25K Hitch
Michelin 17.5 XTA Radials