I did some minimal research and it seems like Maine has a very liberal definition of "abutter". If you say you are, then you are, unless challenged.
From: http://caselaw.findlaw.com/me-supreme-judicial-court/1461500.html
[¶ 12] An abutter generally has standing to participate in and appeal from local administrative decision-making regarding zoning and land use issues. See Sahl v. Town of York, 2000 ME 180, ¶ 8, 760 A.2d 266, 268 (stating that the threshold requirements for an abutter to establish standing are minimal).
[¶ 13] Wister asserted before the ZBA that she is an abutter, identified the location of her property to the ZBA, and objected to Moore's request to “build a road below my house.” The ZBA treated her as an abutter, allowing her to be heard and considering, but rejecting, her objections to the variance. Local citizens participating in zoning hearings need not present deeds, maps, or other proof of their status as abutters to justify their participation in such hearings. See, e.g., Rowe v. City of S. Portland, 1999 ME 81, ¶ 4, 730 A.2d 673, 674-75. A statement of abutter status, as occurred here, is enough to establish a prima facie showing of standing, absent evidence to the contrary.
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Another citation from the Sahl v. Town of York case is interesting:
[¶ 8] Pursuant to Maine law governing appeals from municipal boards, "[a]ny party may take an appeal, within 45 days of the vote on the original decision, to Superior Court from any order, relief or denial in accordance with the Maine Rules of Civil Procedure, Rule 80B." 30-A M.R.S.A. § 2691(3)(G) (1996). To challenge the decision of a municipal zoning board of appeals, a party must "(1) have appeared before the board of appeals; and (2) be able to demonstrate a particularized injury as a result of the board's action." Sproul v. Town of Boothbay Harbor, 2000 ME 30, ¶ 6, 746 A.2d 368, 371-72 (quoting Rowe v. City of South Portland, 1999 ME 81, ¶ 4, 730 A.2d 673, 674-75). If the appealing party is an abutter, the threshold requirements to establish standing are minimal. See Sproul, 2000 ME 30, ¶ 6, 746 A.2d at 371 (stating that abutters need allege only "a potential for particularized injury to satisfy the standing requirement"); Pearson v. Town of Kennebunk, 590 A.2d 535, 537 (Me.1991) ("When the person who has appeared before the board 269*269 is an abutter ... a reasonable allegation of a potential for particularized injury is all that is necessary to establish the real controversy required for adjudication in a court.").
[¶ 9] An abutting owner is "[a]n owner of land which abuts or adjoins. The term usually implies that the relative parts actually adjoin, but is sometimes loosely used without implying more than close proximity." BLACK'S LAW DICTIONARY 11 (6th ed.1990). We have applied the "close proximity" definition to an abutting landowner in similar cases. See Brooks v. Cumberland Farms, Inc., 1997 ME 203, ¶ 8, 703 A.2d 844, 847 (stating that a landowner directly across the street, although not sharing a common boundary, is nevertheless an abutter for purposes of standing). Similarly, in Harrington v. City of Biddeford, 583 A.2d 695 (Me.1990), a landowner challenged the construction of a new home to be located on the owner's street. Id. at 696. The plaintiff's property and the proposed home site were separated by a third lot, and thus were not "abutting" properties. See id. Nevertheless, we concluded that "[g]iven the location of the [plaintiff's] house, a decision by the Board of Appeals that entitled [defendant] to build a house closer to the street than their house rose to the level of particularized injury sufficient to confer standing." Id.
[¶ 10] The Sahls and the Crafts own property across the street from the proposed motel expansion. They appeared at the ZBA hearing. They contend that the motel expansion would obstruct their view of the ocean, and that additional traffic would adversely affect them. These factors are sufficient to confer standing. See Forester v. City of Westbrook, 604 A.2d 31, 32 (Me.1992) (stating that "the proximate location of the abutter's property, together with a relatively minor adverse consequence if the requested variance were granted, such as the threatened obstruction of the abutter's view, sufficiently demonstrates a potential for particularized injury").
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It doesn't seem to exclude neighboring property in another town. I'd check with a good local ME land use lawyer.
