I use a dual-ended separating zipper on latex torsos. A demonstration using a Lisa mask/torso:

Above: You can close the zipper the usual way from the top to bottom.

For quick access or to take a breather, you can also unzip from the top!


You can continue to unzip from the top and the halves separate at the bottom!
Specifications:
Standard diameter at chest: 39" (99cm)
Standard diameter at waist: 32" (81cm)
(this can be altered bigger or smaller but adding room in the
back only goes so far)
Prices are: $450 (with attached mask), or $300
(for the torso only). Shipping extra.
E-mail me for an exact
quote.