If you are truly into racing your car, the best spot for your gauges is in spot where they can be easily read.
That being said, Buschur sales a 2 gauge pod that mounts over the steering column so its not too far to look down at them.
I have the Craig Hardy gauge panel with the Defi gauges. Even though they mount fine and are easy to read, I find this to even be a bit far to look.
And as far as auto-x goes, I hardly look at my gauges during and auto-x. Thats why I got the Defi's....to record and see what my gauges were trying to tell me.
The only time I've looked at my gauges is during track days, when I have enough open straight away to look away from whats in front of me.
Boostin makes a good point, mount them so when they are readin normal temps or pressures, the needles are straight up and down, that way you know instantly if something is off