2014 Nitro sending unit removal

I’ve got some old gas in my nitro that I’d like to completely remove from the tank. Under the center seat is the main sending unit which has Phillips head screws securing it to the tank. Are these “machine” screws and there’s a knurled nut within the plastic tanks shell? I’m worried about removing them if they’re simply self tappers as they may not snug back up upon reassembly. I’d like to siphon the gas completely out and feel this is the best access point at which to extract all the fuel..

Thanks… 😊