The other concern is the sub frame mounts up front. The rubber bushings are normally in compression and not in tension as it would be on a two post lift. Sure, there is a stop bolt to keep the sub frame from relying solely on the rubber bushing to hold it up, but not good for long periods. Same with the rear, mechanically you are ok. But the rubber mounts (and there are a bunch) are not in their normal load positions.
How long are you talking about? I would think over the winter is too long.