I'd keep a battery tender/maintainer on it.
On a small battery, you don't want to keep a constant 1.1 amp trickle on it - overdoing it in the long run.
If you don't keep a tender/maintainer on it, then as suggested, use the trickle an hour or so once a month.
Also as suggested, running the gen monthly is good for it. Perhaps the manual suggest this.
If your not going through much use/fuel, Stabil might be a good investment. I use the marine stuff myself.
Heard a lot of positive on the inexpensive Deltran Battery Tender Jr. I have the Tender Plus model for MCs.
If anything, the HF tenders which can cost around $5 on sale actually works.
So, I'd keep a maintainer on it, run it monthly & use stabil.