In my opinion, anything less than a 75 hp machine with 19-23 gpm would be frustrating to use with a mower. If you get a job where you need to lift or dig a big stump, you will be at it all day with a small machine and then you probably won't be able to lift it. The older, smaller machines, just weren't designed for running modern attachments. Not enough pressure or flow.
I'd either rent or save up for a machine in the 75 hp (minimum) class. You could get by with something like a Bobcat 773-s185 with the 56 hp kubota turbo. The high flow made something like 26 gpm at 3,000 psi which will run a 5' mower pretty good. Low flow was like 16 or 18 gpm at 3000 psi. That will also run a mower okay but the machine is very light and though it has a lift rating around 1850 lbs, you will feel a mower out front.
If you can find a G series 863 with cab and air, it would make a good machine to dig, grade, and mow with even if it's low flow. I owned 2 of them and believe they were underrated in lift capacity.
I have also owned Cat and a CAT 256c or 272 would fit the bill, too, and you can find them used since the D series is out. I'm sure CASE and JD have some good machines in the 75 hp class, too.
I've been mowing and mulching with compact equipment since 1998 and have owned a lot of machines in the Bobcat line up. Anything from 863 up will fit your needs A LOT better than s185 down.