Easy way to deploy two meteor apps running on the same database, with oplog?

Is there an easy way to deploy two apps on the same database, and have them both using oplog properly? This comes up often i.e. when having a main app + an admin app, and you don’t want the extra admin app code clogging up the main app and also trying to interleave two sets of routes with each other.

Different apps same database using meteor up? suggests that just setting the same Mongo URL will do, but I seem to remember that there are some additional hoops to jump through to ensure that both Meteor instances are set up as secondaries for Mongo replication to read the oplog.