I have six breeding girls and like you, I use my stables as farrowing houses. I breed Gloucester Old Spots and all my girls farrow perfectly happily, without being restricted in a horrible farrowing crate. Leave them to do what they do best. Provide them with a creep area for the piglets to go into, with a lamp if the weather is cold and they will be fine. I provide a nice bed of straw, which they make a nest out of to farrow in. Once they have farrowed, they are incredibly considerate and careful not to lie on their piglets. If you watch your girls, they will sniff and move the straw around to see if any of the piglets are there and then carefully go down on their front legs and then lie down. The only time, I have had a couple of piglets lied on is with new mothers getting up during farrowing.
If you provide them with a large enough area to move around in and you have handled your girls enough, so they know you, you should be fine. I would more rather observe my girls nurturing their piglets in the natural way, then to have to go and see one of my girls caged in a contraption, that she cannot turn around in and is restricted like that for weeks on end.
Happy Farrowing the natural way.
Teresa
Pennymoor Herd of Gloucester Old Spots