If minecarts can be placed with a bastion, there is an easy enough workaround by putting the cart dispenser and loader powered rail up a block and out of sight so they have no rail to place it on, but I won't bother making it atm
made with
>about a stack or so of obby
>1 stone pressure plate
>4 dispensers
>13 rails
>5 powered rails
>1 minecart with chest
>24 hoppers
>6 chests
>7 redstone repeaters
>2 redstone torches
>1 bucket of lava (in dispenser)
>9 minecarts(in dispenser)
>28 redstone dust
>4 levers (replaces some torches in pic with them for powered rails)
>1 redstone torch
>1 stone wall/fence/ etc
It is pretty cheap to make, has a cheap upkeep of 2 arrows per use, easy to use for our players, difficult to escape for enemies, and is very easy to kill people with if someone sees them get caught.