You should make a new map where you have a little shop, so you are able to get everything. Thanks! (read my other post about the anticheat called "FIX THE ANTICHEAT")
You can already do this in the various player shops. Not having everything in one admin shop helps out the economy and makes the players rely on each other more. The basics are at /warp grass, anything else you need can be bought from others.
Then add a modpack to a SP map and do it yourself? People play on servers because it's a multiplayer experience. The idea of a single player server is just conflicting.
last time i tried a modpack, it didnt work cause i had optifine. also, i cant get in the server (look at "FIX THE ANTICHEAT") so why not?