Can I leave eyelet uncapped?

Last winter I drained water to below eyelet and then capped the eyelet and covered the skimmer with plate and gasket before covering the pool. Surprisingly, the water rose about one foot over the winter! Not sure how, but I think the cover is pourous (I can see "dots" of sunlight all through it.) Anyway, this caused a crack in my eyelet from freezing/thawing. So to avoid having the water level rise again this winter, I'd like to leave the eyelet uncapped so that any water entering the pool will immediately run out thru the open eyelet (I will use a 90-degree elbow to point the water downward and avoid a direct opening into the pool.) Are there any potential problems doing this? Has anyone tried this before, and if so, how did it work? Thanks!

Last year, did you remove the return eye and cap it from the inside?

No, I did not remove eye, but I did cap it from the outside.

I'm pretty sure the idea is to remove the eyeball and cap it from the inside - that way the fitting that goes through the pool is dry and won't get cracked when water freezes inside.