Was going to edit the farm map to add a minecart there, realized I'd need someone familiar with SMAPI to do it instead, because the new location would have to be added to the list of available minecart transport warps (or simply replace the bus stop one, either way works). If anyone could help me out with this it'd be much appreciated.
Yeah, cant be done, that stuff is hardcoded on a level you cant imagine, adding new starting points is quite easy, but new destinations? Cant be done
I'm no modder, but it seems like an alternative way to do what you're wanting would be to make another exit to your farm directly above the main exit (due right of the drop box), and have it connect directly to the top-left part of the bus stop map, right next to the mine cart. That would make the bus stop mine cart as close as if it were on your farm.