Instead of an expensive monitor use your android phone or tablet a little while ago we looked at using an android phone with a dslr and how the experience was actually pretty good.
Android tablet as dslr field monitor.
You will need an otg cable usb cable for your camera and the app dslr controller.
Use your android phone or tablet for nikon camera as a preview field monitor.
In fact this app gives you a lot more control over the camera rather than just being a field monitor.
Make sure it supports your camera before buying.
In the next step head over to your android or ios device open the wifi from the settings menu and connect to the wifi hotspot created by your dslr for the wifi password punch in the encryption key that you received on the dslr screen.
However this only works with certain hybrid cameras such as the panasonic gh5 and sony a7s mark ii.
Camera connect control free or qdslrdashboard paid for android.