This sounds like the age old proverb of "Good, Cheap or Fast - Pick Two"
I like your original suggestion, but you do have options:
- Close all channels, wait an hour, then restore the new lnd node w/ your mnemonic seed and password.
- Close all channels, wait an hour, send an on-chain transaction from your original lnd node to the new lnd node.
- Dont close anything, save your static-channel-backups file, restore with the static channel backup/mnemonic seed and password and wait patiently for multiple days for the funds to be recovered due to force closes (Please don't do it like this)
There are other creative ways to do this (opening new channels on the new lnd node and transferring the funds through invoices or something), but i've stuck to simple examples here.
To move to a new node, we'll have to take your channels offline (not network friendly). We'll have to take them offline, close them, and then reopen them on the new node, so your best bet is to use the option that you are comfortable with.
Closing your channels, then on-chain transaction to the new node may cost more sats due to transaction fees, but it is an easy and fool-proof way to migrate your node.