Hi Jillius, I really admire you're positive and philosophical attitude. Good for you. You say you have tried everything, I presume you have tried some of the more obvious alternative therapies such as, homeopathy, holistics or accupuncture? I can only personally extoll the benefits of accupuncture, not for psoriasis I hasten to add, If you haven't tried it, then it may worth checking out a decent practitioner in your area.
I had a long term girlfriend a few years ago who suffered badly from it and as you yourself pointed out, it only really cleared up when on holiday in the sun. Whether it was the removal of day to day stress, the sun, the sea or a combination of all three, I'm not sure. Have you maybe considered winning the lottery and moving abroad : )
She also dreamed of going to the Dead Sea which as you know is like a normal sea with added salt. And I'm pretty sure that you can buy Dead Sea salt crystals which you put in the bath. I think she started using them near the end of the relationship, so I'm not really sure of the results but again, if you haven't tried them already, it may be worth a try.
All the best
G