Other than a mounting location for your anchor light, does that top foot of mast actually do anything for you? If not, cut it off and remount the anchor light.
Keep it simple.
Dave, and others...
This is how I feel too. The top of the mast just holds the anchor and spreader lights, and, of course "looks like a boat". One of the drawbacks of a tilting mast is that I must always remember and prepare to enter the slip, and must have some mechanism to raise and lower the weight of the mast and radar dome. Then when the mast lays down over the stern, making it hard for me to access the flying bridge for any usage or repairs topside while I am docked. There is another boat in this marina with a tilting mast, so I could see it first hand.
I am inclined to just shorten the mast, even though the "look" of the boat changes. However, that is cosmetic and personal.
As it turns out, the current radar dome is right at the height limit for the roof, so I will need to lower the radar dome, then remove the top of the mast and rebuild the spreader. On my trial run, I tried to enter the slip with full tanks (fuel and water) so when returning home with empty tanks, I will be riding higher in the water, with less roof clearance. So I have to plan for this in the final mast height.
I have found anchor and spreader lights at the usual suppliers (Fisheries, WestMarine, Defender). The current wiring for those lights travel up a hollow channel inside the center of the mast. I will need to make cuts in the mast with a reciprocating saw or panel saw, trying to preserve the wiring so I can splice in extensions to the new lights. If not, my guess is I will have to feed new wires down the channel and out the bottom of the mast (where the current wiring travels). Its a bit of work, but in the end it would keep things simple, strong, stable over time.
This is my inclination. I have not done anything like this before, so I thought I would see if others find my plans a bit strange. And I will need to find another person to help (this is a 2 or 3 person job). Thanks for the feedback.