swapping out ice bottles is really not that bad. seems like you're making a bigger deal out of it than necessary.
I use the ice bottle method as well and its really easy. I have 1 gal milk jugs, 1/2 gal milk jugs and 12oz bottles that I keep frozen at all times in the freezer in my garage. Depending on how much temp I need to drop over a specific amount of time determines which size bottles I use. I also tend to use the smaller bottles during the day to hold temps and the larger for overnight since they obviously take longer to thaw. After a few days you get really good at choosing which ones are appropriate.
If you do use this method one thing I would suggest is also using a beach towel or something similar at the bottom of your chamber to soak up the moisture from the thawing bottles. I have never had a problem with mold this way and when you feel the towel is alittle too damp, swap it out with a fresh dry one.