RE: Compact Broadcast Node: Low Cost Infrastructure to support Keychain, Splinterlands, Steem Engine and Future Apps

You can follow the exchange node guide in the official repo (also using docker): https://github.com/steemit/steem/blob/master/doc/exchangequickstart.md

An exchange node is basically the same as a seed node, you can just skip the part about tracking account history for a single account.

That hardware is more than enough to accomplish this.