I was going to say, but I see you done it yourself, they just grabbed mine (I have same 2016 Forza) with a towel and twisted it by hand, pushing it up a bit..., you can also order those spanners from Lazada, not expensive...
When I got my Forza first (used) , a few years ago, I was doing a bit of kamikaze riding around corners, to see it's limits and excitement of a new bike etc. (!) , scraped the center stand a few times, and generally noticed the heavy back end was very bouncy and unstable around corners. So I change the preload to max , shortest setting, it helped a bit. I understand with heavy luggage or a passenger this setting is also useful....
Don't worry about it effecting center of gravity etc. , generally it's just a small change...
One of my back shocks started leaking few years ago, so changed both with the same used ones, going okay so far. Then of course the front forks leaked last year, repaired those too, and a lot of other issues, nowadays it consumes oil, bad news...! , when people say, Honda bulletproof, I laugh out loud ... ???? !