</font><font color="blue" class="small">( Fluid in the rear tires is a good start, then I add my BB and have no trouble... )</font>
I agree with the fluid in the tires...but that's more for stability then ballast...IMHO.
And, unless your back blade goes 500 plus pounds...it's not going to be as much help as you'd like. I used a very old and very heavy rear blade...heavier then most of the blades I've seen. That didn't really help much for ballast.
rk246 is discussing a Box Blade, of course, but I think you'll find you really need more weight then that.
When I used the blade described above, normally I'd just spin tires when going into a dried out, clumpy pile of gravel. When I used my ballast box (in conjunction with a tooth bar), I dove right into the pile.
I think you'll find you'll want a considerable amount of ballast. My opinion is a ballast box will work better then most implements. You'll know what you need when you try digging...