There is plenty of clearance between the tailgate and the front of my Sabre, which also looks to be very simular to the Columbus... but I've noticed on some 5th wheels, the lower front panel is much more vertical than on the Sabre which can really cut into the tailgate's space!
I have a friend with a 2002 RAM3500 LB who had to remove the tailgate to connect to his 29Ft Cruiser Fifth Wheel.
Take a look at the pictures and you will see what I mean!