what's the weight of the boat? Unless you're going to be over weight for any bridge span formulas, you'll be fine. Most states permits aren't even all that expensive, quite cheap really.
I've been on the phone with the DOT from many different states and pulled all kinds of permits for inordinate size vehicles, every state has different laws.
Also, most states will not allow you to run after hours or on the weekends with a permitted load.