I have 2008 Hunter 38 and while I didn't run radar, I did install GPS and AIS antennas on the arch.
Feeding the wires down through the arch to the aft cabin was not terrible. There is access cover in aft cabin on starboard since above the headboard that gets you to the arch feed. From there went through the access door next to the bed to feed wires across back of the boat.
Then the fun began.
On the port since there is a chase that feeds above the liner in the aft cabin, outboard if the lazarette (in fact if you open the lazarette and take the stuff out of it you can see where it opens to the lazarette) then above the port side hanging locker past the head and to the nav. There is a conduit that runs the distance, but I found it packed full and was not able to get the wires in. So I went next to the conduit 4hours, numerous scrapes on my arms, two serious cuts, and blood everywhere I managed to get it done with a great sense of pride.
What I learned that could help you.
The fabric head liner on the port side in the aft cabin easily pulls down (there is a seam with what looks like welting about a foot in from the hull where it pulls out) and easily with a plastic putty knife reinserts.
Above the port hanging locker where the shower sump discharge is the panels snap out easily so you can get to the wire coming from the lazarette and feed it past the head.
Same kind of snap out panels at the nav seat where the head bulkhead is.
Getting the wire to feed past the head was a nightmare. Couldn't get the wire fish to go from either direction easily. Once got it 3 feet in and could not get it to move in or out and was getting ready to cut it off when the gods smiled and it unhooked and came out.
In the course of this, I did learn where the pre installed hose for the high water bilge pump goes. It is laying on top of the holding tank ready for you if you ever want to install the high water emergency pump. In that same place I discovered there is a coax terminal for the TV should you ever want to have a TV in the aft cabin. There is also a set of wires that look to be 12 volt (red and black) that I'm thinking may be for 12 volt TV but can't be sure.
As for going from the pedestal guard down, I suspect that you either need to remove the floor plate in the cockpit where the autopilot is located, or look at removing the cover that is built in the ceiling of the aft cabin.
I thought Hunter did a nice job of pre installing some of these things, now if they'd only publish a page that went with the boat telling us what they ate and where they are located, we'd be golden.