The first day I brought my new L3301 home I was a moving a trailer around with the front end loader, no rear implement. At one point as I was backing up my sloped driveway in front of the shop, I thought I had backed over something as the tractor started to tilt. Then I thought that maybe my dealer had somehow not attached the front axle correctly or some major mechanical mishap! THEN I realized it was a simply a case of having zero ballast. I was spoiled by my much smaller '95 B2105 having fluid filled rear tires and usually, almost always, having some sort of implement on the rear.
So, 2 days later, after a trip to the local commercial truck supplier (55 gallon drums of windshield washer fluid for about 100 bucks each, I ended up using one plus 8 gallon jugs so returned one drum) and buying the trick little Schrader valve to hose bib fitting (NAPA, ask for the fitting made for putting fluid in tires, about 10 bucks) AND the proper arrangement of the garden hose divider valve (you have to allow the air to get out of the tires as you fill, partially fill, about 75% with the valve stem at 12:00, as you pump in the fluid) I had my start on counter weight, REQUIRED.
Now that the tractor is in daily use, I always have something additional hang off the rear, now it's my 5' box scraper. I just used my forklift attachment to off load a trailer with several thousand pounds of steel, and ran out of lit power with the FEL before raising the rear end. So for me anyway, fluid filled tires and an implement provide the needed counter weight. I see some comments about "increased wear on the bearings" or other stresses caused by packing the weight around......it's a frigging tractor, it's made for this, any accelerated wear is going to be infinitesimal!