My full node and lightning wallet is finally functional. Thanks for the guidance of @Stadicus3000 and @rootzoll.

These are the tutorials I used:

https://github.com/Stadicus/guides/tree/master/raspibolt

https://github.com/rootzoll/raspiblitz/blob/master/home.admin/50copyHDD.sh

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Needed to change the RaspiBlitz script to install the Bitcoin Core 0.16.3 instead of the now unavailable 17.0-RC3.

For the HDD I used this X820 expnsion board http://www.raspberrypiwiki.com/index.php/X820.

This way only one power source is needed and will be nice and compact once housed without the LCD on.

https://i.redd.it/7mubrhcyl7n11.jpg