ok it's down, and the boat was transported yesterday to Bayport Yachting Centre in Midland. Unfortunately didn't get a picture of it coming down .... .that sucker is heavy. A multi person job for sure. 4 in this case. I will take pictures when I'm up there again in the next couple of days.
The bolts were gooped up with 4200, so came out ok. As Scott said there are 4 nuts and bolts per post, through the deck with a backplate on the underside. 1 post is accessible through the access panel in the aft cabin, and the other 3 are accessible through the port lazarette and the two aft lockers.
While the screws were (mercifully) gooped with 4200, the guys at Angus Yachts used 5200 on the feet of the arch ..... uggggh. The heat gun didn't seem to do much through the stainless which was a surprise. Only way to get it free was a mallet and metal wedge. The guys from MacRae Marine in Hamilton did a great job with this. I highly recommend them. No damage at all to the gelcoat.
Once the posts were freed, it was a matter of disconnecting the wiring for the speaker pod (just a simple connector), and laying down the arch and securing it for transport.
Covered the holes through the deck with shrink wrap tape to keep everything dry.
Next job will be to scrape the 5200 off of the deck and arch footings. Will try the heat gun again as well as a couple of adhesive removers (including Re-Mov as suggested). Practical Sailor says that Marine Formula by DeBond Corp is the best but you can't buy that in Canada for some reason. I think they got in trouble with product mislabelling and are banned for now. Will let you know how all of this goes and will post some pictures.
And then it'll need to go up again.
Thanks everyone for your help and suggestions.