I have a couple of alternatives. What I was originally going to do was use a scrap cultivator. I planned to cut off the ends to the size I needed, build a plywood form around what was left and pour it full of concrete. Then I could strip the form or just let it eventually rot off on its own. The cultivator would give me the 3-ph attachment points and the part embedded in the concrete would act as rebar.
Then a local contractor dropped off some pieces of what I think were once composite concrete/brick ornamental gate posts. They're various sizes, mostly a little less than 2'x2' and assorted lengths. They looked so much like the concrete blocks used as barrier, ballast etc, that I decided to use them. I picked up a 3-point hitch fork lift. It's easy to back up to one of the blocks and pick it up, then put a chain around it to hold it in place (it would be embarrassing to have it slip off the rear fork in the middle of a lift) This way I have another multi-use implement instead of just a weight. Since I have forks for the loader, I don't expect to use the rear forks very often, but they're there if I need them.