A small VPS is mostly an exercise in saying no. The default image arrives with a database, a cache, a second cache and a file-transfer daemon, and between them they take a third of the memory before a single visitor shows up.
The honest check is systemd-cgtop for a minute, then turning off
whatever you cannot explain. A static site needs a web server and nothing else.
An untested backup is a rumour. The restore is the feature; the copy is just the prerequisite. Put a calendar entry on it, restore into a scratch directory, diff against the live tree, and write down how long it took.
If the answer is "I am not sure it would work", then it does not work yet.
This site has no build step. Three files, one stylesheet, and a text editor. It loads in one round trip and it will still open in ten years, which is more than can be said for most of what replaced it.
The trick is not discipline, it is scope: once a site needs a database, it needs everything else too.