Can someone be the town highway superintendent of one town but live in a different town?
Yes, but only if there is a state or local law that allows it.
In 1987, the New York State Attorney General wrote an opinion that indicates that the town board may adopt a local law to allow the town highway superintendent to reside outside the town. This opinion is based upon an amendment to section 3(16) of the Public Officers Law regarding the Town of New Castle in Westchester County.
Towns should discuss the issue with the town attorney before adopting a local law impacting the residency requirements of an elected official.
Resources
1987 N.Y. Op. Atty. Gen. (Inf.) 119
Office of the Attorney General State of New York
Informal Opinion No. 87–52
July 1, 1987
MUNICIPAL HOME RULE LAW, §§ 2(5) and (12), 10(1)(ii)(a)(1); PUBLIC OFFICERS LAW, § 3(1) and (16); TOWN LAW, § 23(1).
Office of the Attorney General State of New York
https://ag.ny.gov/sites/default/files/opinion/I%202000-5%20pw.pdf
Opinion No. 2000-5
May 18, 2000
MUNICIPAL HOME RULE LAW §§2(5) , 10(1)(i) and (ii)(1)(a), 22; PUBLIC OFFICERS LAW § 3; TOWN LAW §23.
Office of the Attorney General State of New York
Subject Index of Opinions since 1995
https://ag.ny.gov/appeals-and-opinions/subject-index