It would be interesting to see which ones of these services generate the most logs, and disable them individually as opposed to disable all logging activity.
Looking a bit into this, it seems there's also the possibility of enabling in-memory only logs so that disk is never written to but the information is still available during that session. I'm not sure how this works but I'm curious about it so I'll dig more into it.
EDIT:
I looks like it may be as simple as editing /etc/systemd/journald.conf and set the Storage option to either "volatile" or "none".
Storage=
Controls where to store journal data. One of "volatile", "persistent", "auto" and "none".If "volatile", journal log data will be stored only in memory, i.e. below the /run/log/journal hierarchy (which is created if needed).
If "persistent", data will be stored preferably on disk, i.e. below the /var/log/journal hierarchy (which is created if needed), with a fallback to /run/log/journal (which is created if needed), during early boot and if the disk is not writable.
"auto" behaves like "persistent" if the /var/log/journal directory exists, and "volatile" otherwise (the existence of the directory controls the storage mode).
"none" turns off all storage, all log data received will be dropped (but forwarding to other targets, such as the console, the kernel log buffer, or a syslog socket will still work).
Defaults to "auto" in the default journal namespace, and "persistent" in all others.
Some interesting thread on the subject: raspbian - How to disable logs? - Raspberry Pi Stack Exchange