The Replacement Clear Lens for Omega LED RV Porch Light # 328-89-319 is approximately 4-1/2" x 4-3/4" and is the direct replacement for the lens of the Omega LED RV Porch Light with Switch - 357 Lumens - Surface Mount - Clear Lens # 328-007-30SCPE.
I do recommend ensuring you have this exact porch light model as opposed to using dimensions in order to confirm the fit. I have added some links below to video reviews for you to check out as well if you'd like to take a look. view full answer...
You'll have to measure the outside dimensions of the base of your 22 inch Blackstone but the most likely to fit MORryde Generator tray would be the part # MR89RR you mentioned which has inner dimensions of 17-1/2" long x 20-3/4" wide x 2-1/2" tall. view full answer...