Railroad and models without tables

I'd like to use railroad on my Rails model. Unfortunately, as I have to
make some connections to a second database I've got some models like

class LegacyDb < ActiveRecord::Base
        establish_connection "legacy_db"

class LegacyDbData < LegacyDb
       set_table_name "data"

This is fine for the occasional call to the "data" table but railroad is
not at all happy:

`log': Mysql::Error: Table 'legacy_db.legacy_db_data' doesn't exist:
SHOW FIELDS FROM `legacy_db_data` (ActiveRecord::StatementInvalid)

There are a few of these models and they're used in various places so
removing them for running railroad is not really possible. Is there a
means of either preventing railroad from trying to connect to the main
application database for these models?
Thanks for any suggestions.