Just add weight to the rear end. If you don't have a tiller or other attachment, build a three point weight bar that you can add tractor weights to. I can provide a pic tomorrow if you want.I guess the other reason I wouldn't want to use antifreeze is if it leaks because it's so toxic.
I find them at farm auctions pretty cheap. Probably have a thousand pounds of different weights designed to go over a bar with a slot in them.
Also have an angle iron bar mounted to the front loader with three chain hooks welded to it.
Great for hooking up loads and the bar is a great place to hang those weights to push T-posts in without having to use a manual post driver.