Hi:
I am not a fan of adding or subtracting stuff to cars or bikes, but a temp gauge is a useful addition.
There is really not an optimal placement of the gauges in the fairing sides of the 75S, but I made a compromise and put a temp gauge on the left hand side. Some of the wiring is already there, as well as the sender for the fuel gauge. You will have to get the gauge, the temp sender, and a couple of wires to complement.
I decided against the fuel gauge, since the idiot light works, and did not wanted another hole on the RHS fairing. An oil pressure gauge, in my opinion, is not necessary: with the bike idling at good operating temperature, if the oil lamp does not flicker, you have good oil pressure. If you are really curious about it, put a temporary one and measure the behavior for a couple of weeks.
There are enough explanations about how to do it on this very laudable site; if you look you will find my post as well as a number of others.