Easiest is to just let the node run for 15 min. It typically finds a node.
I made a bugfix in Classic that would help as well, it's already in the 'nightly' ubuntu PPA if you can use those.
https://launchpad.net/~bitcoinclassic/+archive/ubuntu/nightly
Yes, I've had all my Ubuntu VPS nodes running Core because neither XT nor BU has provided a PPA for easy conversion and updating. I set up my VPS nodes a couple of years ago - doing so was all the rage on reddit in those days - and I would guess a lot of other nodes were set up just like mine. And likewise, most of those are still running and still running Core because there's not been any big blocks alternative. I should think a goodly number of those would migrate to Classic, were we given a good mechanism to do that. Reference: https://launchpad.net/~bitcoin/+archive/ubuntu/bitcoin
Example:
https://play.google.com/store/apps/details?id=it.eternitywall.eternitywall
This app still needed to connect to a server maintained by the dev of Eternity Wall to get the list of all messages. It depends from it.
With a feature that I'm asking, the app will connect to some random full nodes (as common SPV clients) to ask the list of all these messages.