Ok, that makes sense. My normal layering strategy is a pair of 3/4 compression tights with another layer on top, thin for warmer days, thick for colder days, and then my shell pants. The bottom of the second base layer is always tight, and previously I just folded them up a bit. But I can't double up over the batteries, too tight.
I was searching for pants that didn't have tight lower legs, and it was proving much more difficult than expected. I found some straight-leg fleece pants from LL Bean, but $99? I don't need that, just looser and not cotton and not too much going on around the waist (elastic, pockets, etc). But the other day I realized I should be looking in the men's department, they make a lot more joggers that have looser legs, even with wide elastic at the bottom, but I think it will work. Have a big box from STP with $15-$20 pants to try on.