Update on the temp gauge install:
Bought the gauge from Mr Mighty, and the cables and temperature sender mentioned in this post from e-bay. Overall cost about $100.
Before any further messing with the bike, installed sender and the wiring and fired up the machine. Waited for the needle to move, and then for the radiator fan to kick in, just to check that the electrical part was OK.
Bought a 2" hollow drill to make the hole in the side of the fairing. I decided to install higher in the fairing to clear the tank and avoid rattles.
Since the install was on a curve area of the fairing, I needed to make an adapter to compensate for the variable gap. Had a chunk of HDPE from which I turned the adaptor. The contouring was done by eye, until the max gap was less than my spec (1mm).
Once the hole was done, I reinforce the back with three layers of fiberglass and resin, as suggested in this post.
Had to cut the back protector cup of the gauge to compensate for the height of the adapter plus the three layers of fiberglass/resin.
Installed the gauge, applying a thin layer of RTV between the spacer and the fairing.
The rest is the normal reassembly of all the trimming and plastic pieces.
A few pictures attached, to complete the post.
The most difficult thing: Installing the cable from the sender to the main wiring harness. The thing has to be threaded through a very convoluted routing behind the water pump case, and there is no way to accomplish that w/o removing the front cover of the water pump. Even so it was hard (my wife had to pitch in, as I needed three hands.
How functional is this: I like feedback that indicates something out of normal, even though is not critical (like overheating indicated by the red light). For that, I consider the thing useful, plus it does not look bad on the bike. I need to lean forward a little bit to get the full view of the gauge, otherwise I see the top (as in one of the pictures attached).
Hope this is useful for some.
Alex G.