I wouldn't worry about water puddling. Unless you have them "perfectly" level, water is going to run off of them. There are umpteen different kinds of plastic pallets. A lot of plastic pallets are designed to contain cargo leaks/spills, especially with hazmat items.
As a follow up, the foam pallets worked great for stacking. No cracks, breaks, compression, etc. The smaller 39x39 dimension means less wasted space with my 16" splits. We had a strong rain and no water was pooling on the pallets. I was stacking a full cord on four pallets. Problem is I need more wood. What you see here is less than 8 cords and I consume over 5 per year. I sold my woodlot so I suppose I need to buy a log load.
Highbeam I feel you pain....I just replaced 12 pallets this summer as well. On a good note I found a local company that has 6x6' HD wood pallets that I got, as many as you want for FREE. I got 20 so far because I have to make an additional stacking area behind the garden this year for my syrup production and pool heater wood..... I still hate digging the rotted ones out after 2-3 years of ground contact......messy job and a pain to get rid of. I wish I had a place local that I could get some of those bombproof ones you got, but hopefully in a year or so my monster woodshed will be done and I won't need pallets anymore.....
I think you can just paint them with a few coats of used motor oil and the wood ones last a decade outside on the ground.
This year was the first year that I actually put a pallet nail through my shoe and into my foot. You pull the top of the pallet off and the stringers usually come with it but the bottom boards stay behind in a nearly composted level of decomposition. Well, they nail those bottom boards to the stringers so you can bet there are some nails pointing to the sky and I got one.
Other than bees and a little non-wood eating bug that I can't identify, I have never had any critter issues. Oh an occasional snake skin but our snakes are small and harmless in the PNW. I am about to close on the sale of my 15 acre woodlot. As such, I can't go back and cut the needed firewood from there. I've been scrounging CL for log loads and the going rate seems to be just over 100$ per cord.
That stuff looks handy just wasnt sure if mice liked them? Pretty sure the rate here is around $1300 for an 8 cord load of logs