As far as I know it's not possible to add a Port in DNS. DNS is working with names and IPs only.
To access the cluster by name and Port it should look something like this: <hostame>.destpark.com:8000
(<hostname> = Name of the A-Record in DNS).
(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)
Regards
Andreas Baumgarten