The radar will hold small fishing boats if set up correctly. Windfarms don't appear overnight, they get put on maps and I would guess that an offshore windfarm would show on the radar; the one up here does. Masts? Your bound to be able to correct me on this, but with 22 years of flying over the seas around this island including working for one of the oldest navigational authorities in the world, I have never seen a mast randomly placed in the sea.
You clear the area before making the TD. Most boats (masts & windfarms) probably only do a max of 20 kts so are unlikely to sneek up on you and jump out during a TD. Correct me if I'm wrong, but the Seaking has a blind arc out front of 30 degrees and therefore if a target is in front of you (the place where you are most likely to bump into it) you can't see it unless you continuously make blind arc clearances. When moving towards the target after the let down, having it out front is a distinct advantage. The TD that I have flown in modern aircraft is generally very accurate. Can you home to two military PLBs in a Mk3 yet? Modern SAR aircraft have homers that can track and designate multiple beacons. This is probably more of a concern than having a 330 degree radar and should have been high priority for military SAR. Please tell me where you will put the radar on a S92/EC225/AW139 etc. to gain 360 coverage? Perhaps it should go in an inflatable bag on the side?
You are unlikely to ever see a company's Ops Manuals unless you work for that company. These are normally commercial in confidence for good reason. However, the manuals are written based on the best aspects of all SAR outfits and not just the military. Some of the SOPs would be very familiar to you as they have been created along the lines of military SAR. Some of them wouldn't because they have been written by forward thinking people with an open mind prepared to explore new possibilities. I know this to be the case 'cos I woz there!