I've recently spent a bit of time up the stick, though it was getting de-stepped for new rigging, rigger wanted a fortune to pull new cables and install new lights etc.
It really isn't that hard, I've got mast steps so it was easier.
I put my small GF on a winch through a clutch, but basically I didn't have and faith so I used 2-3 back up system.
Firstly find a spot with no or limited wash, for you down the bottom of FiveDock bay is as good as any. Feel free to use my mooring there, I won't be back on it for a few weeks yet.
How to climb, better if you have bosuns chair.
i put primary halyard on Bosuns and get someone to tail it, but monkey climbing the mast makes it easier for them instead of just winching up.... yes I'm over 100kgs.
Back up systems, lock a spare halyard to base of mast, and other end tie it off... don't just trust clutch. I used a climbing Grigri, or use a prusik knot tied to climbing harness.
3rd backup, I have a sling and carabiner and clip it onto whatever you can, I used steps, or around mast/spreaders, or at the top there's probably shackles with blocks on them... I mainly clip in when in working position.
Now, the trick is get up there without tools and equipment, however trail a small line 6-8-10mm up, then have a bucket or similar with your tools in it, when in a comfy working spot, haul the tools up.
Its never gonna be the easiest job, but doable.
I drilled/tapped new masthead combo, 2 new cables from top down, and drilled/tapped new anchor light, and serviced the tri colour... bloody hours up there.
My first time I was nervous, after that and knowing it was secure and in sheltered area, it was all good... though happy to get down after hours.
I watched a rigger climb up, interesting he actually used the shrouds and inner stays to climb up, his team could barely tail the line fast enough...I had never thought of that
Do feel like a drone up there though!!