How to use Water Bags?

I live in Charlotte North Carolina, I have an in-ground vinyl 16X36 swimming pool, and have applied a lot of the advice given in this forum in regard to closing my pool. After getting the pool very clean and the chemicals right, I plan on covering the pool and using water bags. This might be a silly question since I don't see any advice on how to use them here - but I would rather be safe than sorry! Does it matter if you overlay the bags on top of one another so that it's "air tight," or is it best to leave a little room between each bag for circulation? My pool gets a lot of sun light and it gets hot under the cover. If I leave space between the bags, then according to others I could get vermin like mice, snakes, worms, etc. Thanks.

I think you answered your own question here!
I don't think you have to leave a space between them, heat causes evaporation, since the cover lays on the water, and blocks/seals the air space on top of the water, not much of any evap will occur, any that does around the edges, will just condensate on the underside of the cover and run back in.

Tillysaint, welcome to the forum!
You asked about water bags (a/k/a watertubes) and I'll try to briefly tell you some about them.
The black ones seem to be a little more durable
They tend to break/ leak easily (this may be because birds like to peck at them or the fact that they are poorly constructed and mass produced with inadiquate QC)
Up til this year, every one I have seen was manufactured in Brazil - this year I see they are made in China (and ~ 1 out of 20 comes improperly heat-sealed, so they leak when brand new !?!)
Often times the 'caps' are badly misshapen upon opening the package, making it almost impossible to close them, once the weather gets to ~50 deg , forget being able to close them without first heating the caps so they can resume their original shape (the caps are the rings and plugs 'heatwelded' to the bag where you fill them)
The 'cyclops' (one cap) type tend to roll off of the cover
Sometimes the caps don't want to come off in the spring and the bag rips in the process
Carpenter ants love to build their colonies in them and chew through them readily

If this scares you, it's actually not that bad. These are just some problems I've encountered over the years. Here's some practical advice on using them.
When you fill one, only fill it 75 - 80 % to allow for ice expansion without compromising the bag.
If you have a couple of old hoses and a 'Y' valve for garden hoses, you can cut the hose ~ 6" long add a 'female' hose end to each, screw them onto the 'Y' and fill both sides of the tube at the same time.
Laying them end to end won't keep 'vermin' out of the pool, if they want to get in, they will. However, given their leaky nature, it's a good idea to overlap them a little. That way, if one leakes, you can slide the others around to compensate for the loss of one. (To secure the cover, you can usually leave ~1' between the tubes)

Any more ?s, or if you need me to clarify something I've said, please ask - I, and the others here will help you. Again, welcome to the forum :) - Waste