Perhaps the links below will be of assistance. The first is a link to the state's non-profit corporation website. There you should first use the search function (Corporate Search) to check that there is not already a corporation registered using the exact name of your road association.
The site also provides links to other useful information about forming a nonprofit corporation including a link to the nonprofit corporation act.
The process is relatively straight forward and the second link below will reveal a PDF form for filing as a nonprofit corporation. The sections of the form are as follows: Name, Obviously use the name as is shown in your bylaws, Road Associations are mutual benefit corporations, the registered agent will likely be one of your officers or directors (non-commercial registered agent), your bylaws will determine the number of directors, you will have members (some nonprofits do not,) you will name one or more individuals as the incorporators who will also sign the form.
There is a $40 registration fee and there is a requirement for filing an annual renewal (@$35 as of 2022!). So that is easy peasy. But you should consult with an attorney to determine if filing as a Maine nonprofit will provide the benefits you are seeking and is otherwise appropriate for your statutory association. This is not rocket surgery and most attorneys can answer your questions and help make the filing for only one or two billing hours.
Do keep in mind the following: there are no tax benefits to being a Maine nonprofit corporation, you must renew the nonprofit corporation registration every year, your bylaws and articles of incorporation must agree so be sure to be sure they do, the Maine nonprofit corporation act may allow more powers than recited in your bylaws or in the provisions of the state Private Ways law but your organization will still have to strictly comply with the Private Ways law (Title 23, sections 3101-3106) to benefit fully from that law.
https://www.maine.gov/sos/cec/corp/nonprofit.html
https://www.maine.gov/sos/cec/forms/nonprofit/mnpca6.pdf