WB trim

[PilsetnieksLv]

Hello, I used WB trim option to delete everything outside my WorldBorder. I thought it will remove all land like worldedit does //set 0. But after I did WB trim I realized it deleted chunks and when someone came near the WorldBorder new chunks generated and now it looks even worse than before this. See picture:
https://prnt.sc/pwilbd
(I changed the default range of 260 blocks to 0 as I thought it will remove just blocks, not whole chunk)

My question is: Does there is an option using which I can remove JUST blocks in range 300 blocks from the world border so when players will come to the border, new land won't generate for them but it will just be a hole? (see the picture:)
https://prnt.sc/pwio1y

If my map would be small, then I could just remove land manually by worldedit but its very big and it could take months to manually remove land.

Please help me. Thanks!