Hi,
I have to agree with Mr. WhistlePig

.
With either a BX or B Kubota, a Piranha Tooth Bar will make digging and leveling very easily doable, and you can take the PTB off easily in the winter to use your loader for plowing.
However, in my opinion as someone who has used bushhog mowers in the past, and has a MMM now for mowing several acres of (not really lawn) mixed terrain, if you can find a Bush Hog type mower for your 5 acre area, you will find it meets your needs better than the MMM.
If the ground that you want to work is very hard packed or otherwise difficult to dig, a box blade with scarifiers can loosen that so you can dig and level it easier, and adequate quality used ones are often available.
Roger's post also provides some well thought out options, and he has (if I recall correctly) experience with the BX models, which I do not, except by reading here on TBN what people have been able to accomplish with them.
Happy tractoring and be well,
Thomas
PS:
Can anyone here help me understand the multiple recommendations for a BX rather than a B? The ground clearance and 3-point lift capacities are the significant differences I can see in the specs.??? Is there a major price difference as well?