I couldn't get the leaded crystal glass but these card frames I got at the dollar store work pretty good. :)

These two are located right in the center of my rig's ceiling and are mounted on an aluminum plate because the plate is over two access junction boxes that house all my AC and DC wiring.

I also have a few single card frames on the ceiling in various spots. The card frames are easy to use, I paste an LED panel onto a piece of white aluminum sheet and secure it to the ceiling with a couple of screws. The silver card frame and glass is then slid onto the aluminum sheet.
For connections to the RV wiring, I use one of the included adaptor pigtails with the molex connector. That connector snaps onto the LED panels wiring. Should a panel fail, I can pull it off the aluminum mounting sheet, paste a new one on and connect right back up.
I've tried a few of these LED panels and the ones I came to like are 48-3528 in warm white. Like Mex said, not all panels are equal, it pays to order a few from China and see which seller has the best.
BTW, all of mine are unregulated and have endured voltages as high as 14.9 V. None have failed.