I would ask I used to do this for bear bait I would go into a grocery store talk to the manager he would tell me to come when the are closed it looks bad for both them and you when people see you pretty much dumpster diving during open hours I would also have a waiver with you stating that you release them from any harm that may come to you i.e. stitches, broken bones even your truck/car this may up your chances with them knowing you take full responsibility for your actions and they wont be sued.