I have always put the harness on first and tightened it up, If I am on the line for a long time I find that my back hurts less if the harness is tight. If a wetsuit or other temperature saving device is worn then it is under the harness, the PFD is over the harness and if it may warm up during a sail I put a wind breaker over the lot. I have never gotten hung up on the trap line but I am sure everyone that drowns says the same thing, as far as getting out of the harness if you are trapped, good luck, besides if you are wrapped up in lines under a boat, getting out of the harness is not a high percentage move. I like the idea of a covering over the whole mess to prevent lines from catching in the first place but have
not done it yet. I have been thinking of a uni-device pfd-harness-camelback for distance races and may sew one up as soon as I can get all the parts together.