Personally I’d get the LG. A lot of chicks have been hatched in LG’s. They are not as horrible as many people say. Get it as early as you can and start playing with it to get used to it and get it stabilized. If you are concerned about that and plan to do staggered hatches much, spring for a better incubator. A second incubator used as a hatcher makes life so much simpler if you are doing staggered hatches.
Humidity and turning are not the only issues with a staggered hatch. The first chicks that hatch poop. I have a 1588, not sure which Hovabator you have, but I imagine they use that plastic tray in the bottom that has the water reservoirs. Within two or three days of the chicks pooping in those it starts to stink. I’ve had regular hatches drag out enough that became an issue, let alone a staggered hatch. Also the chicks crawl around. They will slime the later eggs, making it real possible bacteria will get inside the egg and kill the chick developing in there.
I imagine you have the 42 egg incubator. For the later 20 eggs you only need 3 rows in the turner. You can take the other three turner rows out and build a fence across the incubator to keep the chicks away from the later eggs or put a mesh basket over the early eggs to keep the hatched chicks contained. You still will need to clean the incubator after the first hatch. If you can keep the chicks away from the other end there isn’t a lot moving so they aren’t in much danger from the moving parts of the turner.
You can try it in one incubator but I think getting a second for use as a hatcher greatly reduces your risks.