Shouldn't be a problem. Every "community" mailbox I've seen in subdivisions are placed on the right of way. Check the survey for your own home. Chances are you'll find the highway easement extends another 6'-8' into what you think is your yard.
In the town where our daughter moved to a couple of years ago, the neighbors warned them about the USPS trying to get them to install a rural type mailbox on a post in front of their home rather than continuing to use the box on the house.
Note that they live in town and the home they purchased originally had one of those mail chutes that would drop your mail (and water from a garden house<g>) in the foyer.
Sure enough, they got a note from the Postmaster pretty much telling them they HAD to install the curbside mailbox but down at the bottom in fine print was a notation that such would be voluntary since their mailbox was grandfathered in.
Small town but certain area residents have taken a stand and refuse to go with the program. USPS wants to be able to do away with the walking letter carrier.