I second that, you have been very lucky thus far that they haven't eaten the insulation or injured themselves on all of the stuff in there. Horses are very prone to hurting themselves and if they are starving, like your Tequila, will eat just about anything. I know you were worried about bloat with free feeding them, but I would worry much more about colic with the chances of them ingesting the things in your paddock. Or poking an eye out. Or getting a nasty cut. Trust me, a little prevention now will go a long way to saving you money in the long run.