Clovers are really the only ones good for lawn substitutes due to their lower growth and tolerance of conditions here in PA.

That having been said, I attached a list of clovers. While most are listed as pH 6-7 or so, clover's relatively tolerant of acidic conditions--I had no trouble growing copious clover in my starting soil on this property at a pH of 4.7, and my neighbor's lawn is still a high percentage even a decade in.

Except for nitrogen, clover's demands are roughly that of a lawn (lawns are actually fairly average to somewhat forgiving in terms of soil resources).

Areas and individual plots vary considerably due to previous care and previous use, but as a general rule Pennsylvania soils are calcium-leached (as you noted), OK on magnesium, short on potassium, and short on phosphorus. How short, if any, only a soil test can tell you.

No plant particularly likes lacking Ca, K, and P and they'll let you know it. Other shortages can also impact any plant's development; boron is another famous one around here.

What I'm saying is that, if you want effective cover, nothing is going to work in a tapped soil. A $25 soil test and rebalancing would be necessary if you want good coverage that will survive over the medium term.

Here is a link that might be useful: Clover

Would former horse pasture (one property is currentl used as such) be better/worse in that regard?

I can't say what forage grass is used but experience tells me it's probably old K-31 Tall Fescue or something similar (York County), which is more forgiving than, say KBG.