restore wallet using hd seed before 0.17.0 Hd wallets are supported from v0.13.0.
Currently it is easy to save hd seed and restore a wallet from it (due to changes in v0.17.0 and v0.18.0):

dumpwallet (read hdseed from it)

createwallet (blank wallet)

sethdseed (set hdseed on a blank wallet)


How to do this using v0.16.3?
Problems I encountered:

I cannot find hdseed in dumped wallet file, so I don't know hd seed to backup
creating new wallets is done by starting bitcoind and passing -wallet option, but I don't see a way to specify hd seed when creating a new wallet

Is that even possible without upgrading?
I cannot find hdseed in dumped wallet file, so I don't know hd seed to backup

It used to be called hdmaster rather than hdseed.


creating new wallets is done by starting bitcoind and passing -wallet option, but I don't see a way to specify hd seed when creating a new wallet

Is that even possible without upgrading?

No. sethdseed was added in 0.17. Before that, there was no way to restore a seed to a new wallet in Core.