Well good luck, but keep in mind. If you are doing an NA server, you will compete with BBG Bot Survival (and not win as they have been the Pillar of the NA side of the community since about July of last year and always get a 60-100 pop every night basically since then). And if its an EU server, well you are still competing with BBG, Rebirth and 15th HvB for the very limited amount of people playing bot servers nowadays.
Siege mode also is the worst overall mode in the game with far more bugs, one reason why BBG's way of doing a Bot Mode is very successful (along with their scripts + admins to deal with most thing). Unless you get a script to set a cap to the attackers then you'll be doing lots of Swaps to keep the balance and unless you also have a script to adjust the bots you'll be doing lots of number changes, depending on how you do everything.
But good luck