I think I see another bridge in the shot.  2nd shot, middle of the screen, lower part.  There appears to be a 3rd bridge on the R side, middle as well.  Even if those bridges are destroyed, you can still get to base.  Just have to take a scenic route. 

Oh how I HOPE for Artillery, mobile and/or stationary. 

  I hope we are able to use "Land Mode" for it as well, but having someone spot would work nicely too! 
