You did say it was an AG and I just assumed you wouldn't be draining below the skimmer and return. Ice causes a problem when it freezes and expands with nowhere to go. Pipes break when ice plugs form with water between them freezing later and the prior ice plugs don't let the expansion take place. If you leave the hose off and do the foam thing anyhow you'll be OK even if the water or ice level creeps up over the winter.
Al