STAA vehicles (Surface Transportation Assistance Act of 1982 "increased dimensions") are by Code of Federal Regulations allowed on Designated National Truck Network Routes.
Tandem trailers not exceeding 28' each in length are covered under STAA guidelines.
The C.F.R. and many states statutes have provisions that allow a certain amount of miles off these routes for reasonable access.
Personally, it's a risky situation even for CDL drivers with the best equipment designed for tandem pulls and I wouldn't recommend it.