I've used roof tab shingles under chain link and stockade fencing to reduce/eliminate mechanical trimming. They last much longer than 30lb felt, and stay put. Little bit of fuss at first, getting them to settle-down and kill what's underneath, but only need to be touched up every 5 yrs or so. Mower decks that are wider than wheel track won't disturb them by not driving over the tabs. Line trimmer gets used a LOT less if at all, and the look from afar resembles that of a carefully applied glypho 'chem-trim'.
Common complaint of "I sprayed and they came back" shows that 'chemical trim' may only account for actively growing weeds vs dormant seeds. Weed burners are great for some sensitive locations, aren't a permanent fix either, but are very effective if you 'burn' ~half as often as you mow.
btw, This could be simpler than having the little lady ask for chemical-free bug control. (always take the easy one

) tog