Seems to me that encap routes learned by rip44 should be fairly persistant - I'd say they shouldn't expire for a day or three or more. Perhaps a week?
Unless replaced by a newer route for the same subnet, of course.
That way if the rip sender (amprgw) should happen to go away for a while, things will still function. And you'd have time to switch over to using the encap file if the outage were to be prolonged.
There's no harm in having a dormant route in your table for a while when a gateway permanently goes away.
What's the maximum rip44 route expiration time setting?
You could, of course, decide to NEVER expire them. With daemon modification, they could be persistent across reboots and only purged when manually selected. - Brian