It will be far to difficult to mount a tri-colour or a 360 anchor light with the mast stepped.
You would have to feed a wire down through your mast and without conduit this wire will find it's way over and around everything that is already inside your mast. You will have to make a weatherproof connection at the masthead. You will be drilling holes in the masthead or the mast itself.
There is simply to much to do while sitting in a bosen's chair 40' off the water.
I know myself that I cannot sit in my bosen's chair for more than 20 minutes as it just gets to uncomfortable.
When I installed my 360 anchor light I was unable to attach anything directly to the masthead and ended up making a mounting plate that was then attached to the masthead via the spinnaker bales. I drilled a hole in the side of the mast for the wires to enter the mast and installed 1" schedual 22 conduit.
Unless you are willing to spend some money and do it properly I would stick with what you have and make it work.
Also, may I suggest that you inform yourself better as to what you want to do with someone who knows there stuff and also may be able to give you a hand.
Do not buy LED light bulbs and expect to replace the incandescent lights bulbs with them. First you will not find an LED bulb that fits your steaming light fixture as there is not enough room inside the fixture for one. Second it will not be Coast Guard approved.
I can tell you that your steaming light takes a 12v 10w #90 incandescent light bulb, that will save you one trip up your mast.
Good luck, I have a feeling you are going to need it.