Find an old Commodore or Atari RGBA (analog RGB) 13" monitor from their Amiga/ST lines (e.g. 1902/2002/1080 on commodore and I forget the Atari model #'s) and then make an adaptor to go into the analog RGB port.
They sync at 15.75KHz and have built in isolation. Quick, easy.
For crosshatch/color, pick up a really cheap JAMMA board off of eBay. Even one that doesn't work but ask the seller if it will work in test mode. Run thru a few games in MAME and test out their test modes to see which ones produce the best monitor patterns for you.