I had a similar experience a few years ago, travelling behind a car carrier full of volvo's, it went under a bridge on the A1 and took the roof off the last car on the top teck, it flew right over the top of me, shat myself!!
Your not wrong, on their 99/00 tour of Kupres, 32&60 Sqns managed to trash the FRV hanger doors 3 times in 6 months by driving through in a DROPS with the hook up. On the last occasion they brought down not only the huge steel doors but also the front hangar wall. Other highlights of the tour involved; smashing a DROPS and JCB through the BFBS relay station's cables next to SHQ and managing to jam a DROPS sideways in the Kupres tunnel.
A similar incident happened in Stevenage circa 80/81. A street lighting truck traveling along the road with the cradle arm partly raised ensued by a loud scrapping sound as it passed under the concrete footbridge linking the shopping centre to the railway station. Result was the truck ended up firmly jammed at 45 degree angle under the bridge as the platform arm acted as a cantilever.