I will add my $.02. If the only difference in catching and missing fish is the trailer, then you have a compelling case for the pork being the problem. I used pork for years. With all the plastic options now available I have no need to mess with it anymore.
While 12# mono may be a little light for jigs, I have caught many jig fish on 12# Trilene XL. Like Bluebasser86 I do not like braid for this application, although many use braid, or braid and a leader for everything. I agree also that PLine CXX (what I use) or another copolymer like Yo Zuri Hybrid would be a better choice. A good 100% flourocarbon line may be a little better, but is not necessary.
I have used the SK jigs with good success. Trimming the weed guard, or just spreading the bristles may help. Sometimes trimming the number of bristles, rather than shortening them all is a better option. As already mentioned, make sure the jig is sticky sharp! Good luck.