Our new truck has created the same problem. However at my tailgate I only have 4 1/4 so off to the shop to get it raised as no way am I only going with that. In any case 5.5 imho is cutting it close. Only time it should be an issue is dips, rr track crossings stuff like that. Previous truck had 5.5 at the tailgate and there were two spots on the way from storage to the house that I sweat one was rr crossing right outside the storage area and another was a dip in the street in our neighborhood (it wasnt the dip so much as it was the grade on each side of the dip). This dip was not really a dip in the normal sense it was more like they raised the road at the entry and exit to the dip instead of a true dip and spread far enough apart that the truck would be going down the exit side while the trailer axles were still going down the dip. I never hit but made sure to go slow and be very careful and it was close less than 1/2 inch clearance and that was being very careful. So in general yes should be ok but you will run across some spots where perhaps not.
