You should bear in mind that there are two view modes, Equatorial Coordinates and Horizontal Coordinates and they behave differently in the same sense that an EQ mount rotates with the sky, while an Alt-Az maintains level to the horizon. The space key will switch between them. The Lock To Celestial Pole option in the FOV settings will display the orientation with regards to Equatorial mounts while in the Horizontal Coordinates view mode. With this in mind, you do not have to work out the orientation for different parts of the sky as the mechanics of the mount get taken into account for you. You only have to enter a rotation value relative to the OTA.

Edit: Also worth noting. HiPS DSS overlay requires internet connection. Which may not always be available. Hotspot tethering to you phone or internet enabled tablet is one field option.
If you do not have internet access in the field, one other option is creating flags. These are little markers you can place where you wish to center the frame, and you can title them. I like to add a predetermined rotation that works to the title as a note of what orientation I should aim for is.

Fortunately, "in the field" for me means out the garage and down the driveway; so I always use Ethernet to connect from the house and have access to the internet. I will have to practice with the FOV symbols and their orientation to really understand how to best use them, but as I mentioned earlier - it has to STOP RAINING first!

thanks,
Ron