I also edited the walk sign itself to tell sims to walk to the hole before anything else, so if you use the “hole in the ground” to tell sims to leave the lot the nearest portal by the time the game makes that check will be the one placed over the hole. I decided the simplest solution was two global mods: One tells witches if they’re nearer to one of my “holes in the ground” than the mailbox/phone booth that they shouldn’t fly, and another tells sims to always use the pedestrian portal nearest them. Sims sometimes insisted on walking away to a different pedestrian portal and witches always wanted to fly. Plopping a pedestrian portal over the newly-made-functional hole wasn’t quite good enough though.
As for the walk sign, I cloned one and made it look like 1t2 “hole in the ground” (it’s only the sign and a literal circular hole for the dirt around the hole you’ll want to get 3t2 miner hole, which C&K included in the link above).
You can get buyable portals and a portal revealer (you’ll need the revealer to get rid of the portal after you place it or to move existing portals). So as I understand them the castaway stories portals were like a combination of a pedestrian portal (the thing that marks where on the lot sims should enter/exit) and a BV walk sign (which gives you pie menu options for sending a sim to another lot).
