Yes, an oil pressure gauge is important, it's unfortunate that Nissan only provided an idiot light that let's you know when you engine is likely already damaged beyond repair that there is no oil pressure.
I purchased an EVO gauge and Gale's A-pillar pods. You will need a couple of things.
Most importantly:
2113-02-02-02 Description: Female BSPP TEE w/ Male BSPT Run Adapter
3036-02-02 Description:Male BSPT x Female NPT Pipe Adapter
Credit: Full details are here.
DIY: Oil Pressure Gauge