You might want to consider something else to do with the land instead of finish mowing 20 acres. Even 10 is alot, but depending on obsticals, ~3 hours on a 84" Zero-turn.
Anyone around there that can make hay? Just how hilly is it? Could it be farmed....beans and corn?
IF those dont work......I'd be looking at something like mowing ~5 acres around the house with a finish mower, and do the rest with a bushhog monthly. Grass dont get real bad after a month. Especially on an area that large. But what are your intended uses with the 30 acres other than to mow.
Here is what waiting a month, and mowing at ~4" height looks like with a bushhog. (and this was mowed way faster than any finish mower would have done it)
View attachment 481811
IF you want it finished mowed.....you are gonna have to do it every week.
I'm definitely starting to like the brush hog idea. I do not know of anyone who can make hay or farm it but I'm sure it is possible.
Here is a pic of the front part of the property. House will eventually be on top of that hill.


The neighbors on both sides are mowing it now, they both hated the overgrown look from the previous owner.
I'm going to take a look at several used tractors in the 45 +/- range and see where I get from there