Fuel pressure gauge

I recently replaced my thermaquad with a Demon. After the thermaquad was rebuilt it was flooding really bad. Fuel pressure was tested as around 7psi which from what I read was high for a thermaquad- however it ran with that pressure for years. So, I decided to try the Demon- Damn that opened up something to give me a ton of power. But now I am curious about the pressure.

Seeking advice on type of gauge, where to place it, are they only able to be mounted in engine compartment? Is there a type to read in the car? Any dos/donts etc are appreciated.
From my experience, if you put a gauge under the hood, the gauge will get hot and read erratically. BUT I have one that I use, under the hood. So........