Hey creekrocket! Sorry for your losses. How are they getting in your pen? Regular chicken wire is easy for them to get into as the wire is thin. 1/2 hardware cloth is a heavier guage and is very hard for them to get into. You can get in at lowes and home depot. I read on another post that if you can pry the pen open with a stick or something they will eventually get into it. I have been lucky because they seem a bit more interested in my compost pile and I have trapped many possum and coons as you know. Hope your luck improves.
My pens are air tight.... My son was gathering eggs the other day and didn't latch the"latch" properly. The coons got in and did their business... We've had several birds out in the yard trying to get back, but the coons keep knocking them off....Until now.