I also welcome you to the forum.
I would tend to agree that you shoud be fine with a 12 ply-rating, load range F tire.
However, many who had 8r19.5 have gone to a 225/70R19.5 size tire. And they've also gone with the popular Toyo brand where in that size, you can get the M143 with 14 ply-rating/load range G.
For a description of the Toyo M143 in the 225/70R19.5 ...
go HERE (randomly chose Priority Tire to get the description)
You may want to consider doing that --changing all tires to the 226/70R19.5 Toyo M143, load range G, 14 ply-rated. That way, you'll get an excellent quality tire at a good price with a 14 ply-rating and load range G.