Isn't it possible to just copy tables of contacts, groups, mailings and their related data into the new install? I'm trying to figure out which tables contain essential data on contacts, activities, donations, etc. vs the ones that contain information on the site setup (like the civicrm_menu table, which I definitely want to leave behind, as somewhere over the years it got corrupted during an upgrade and has double entries and lacks a few entries as well).
Would this at all be a valid approach?