There are different laws for each state - but, many have set the max overall length at 65' for non-commercial vehicles and non-commercial licensed drivers...so the set-up mentioned with the Subaru would be no problem in those states. I would check my local laws.
Would an over-length RV ever get cited? I don't know, but if there was an accident, it could become an issue.
While a remote risk, there can be a chance that police would set-up vehicle enforcement stations near where RV's collect...equipment enforcement includes weight/length/license checks.
Like, in the mountains near a very popular off-road area in SoCal, police where stopping RV's for this purpose. An acquaintance of mine (who was driving a MDT Super C and towing an enclosed trailer loaded with off-road toys) was ticketed for exceeding the legal weight allowance of his drivers license...His trailer's GVWR required an upgraded license type
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Knowledge is power
Safe travels