Woody - I am not sure where you are at. Or what you are running. With typical airboaters I would have to agree with waterlizard, you typically will not need anything.
On the Louisiana and Texas Coast there is lots of marsh that is covered with what most people call wiregrass, marshhay, or cordgrass. This typically has very little water in it and the friction from running distances on grass can warm the polymer up. The doodlebugger or seismic crews found that a sprayer with some liquid will give a little slicking action to your boat and you can run longer distances alittle easier. But we are talking running a mile or more on dry grass at times. Running cutgrass or sawgrass like in the Glades when there is no water can get tough at times as well, and a sprayer helps IMO.
But understand this not to protect the polymer but to lubricate the bottom and help you slide.
In these situations, they used sprayers with water, soap water, and once upon a time diesel. However the diesel is a big NO NO and you will get skinned alive by resource agencies. You might want to talk to the State game agencies before you do that. I have been told that Florida has outlawed sprayers, but I cannot say that is anything other than just rumor. So check that out.
Before I would use anti-freeze, make sure it is not ethylene glycol, the standard green type, as it is toxic to lots of critters. There is a environmentally approved anti-freeze on the market that you should think of using or just ethyl alcohol. I think the use of Ethylene Glycol, standard type antifreeze would get you in lots of trouble with resource agencies if you were caught using it, plus how knows what it could do to critters. And last but least, there are lots of people that could get mad with you using it and get airboaters lots of bad press.