Slim, obviously sarcasm has little to no effect on you!
First, I am a Florida native, where the OP is from, and unlike your gorgeous Mulies, most FL whitetails don't top the scales over 100 pounds! We joke that they are more akin to German Sheppards than deer! On top of that, in most of the oak heads and cypress swamps where you find the deer concentrations I hunted in the central and south FL regions, your shots were rarely over 100 yards. My longest was ~200 yards on a big hog, but was the rare exception.
So, inside that context, is a 300 WM really necessary, since you are shooting in essence large dogs inside 100 yards? I'd argue that its too much! Do I think negatively of 300 WM or 7MM Rem Mag? Nope, they have their place.
Now, change the scenery to what you are showing with sage and ridgelines, up the size of the deer and increase the distance, sure, you can make an argument for 300 WM or 7mm Rem Mag. There are other calibers that will do it, too that are not magnums. Personally, I think you are a glutton for punishment with the 300 RUM unless you are handloading reduced rounds, but that's just my opinion and with $.50 might get you a cup of coffee. Although on second look, the distortions in the photo might be a brake on the end of your barrell, so your felt recoil might be less than normal...
As for my hunting credentials, you won't see any deer as big as yours, but I've managed, thanks to the USAF, to hunt Florida, Washington, Oklahoma, New Jersey, Texas, Alabama, Illinois, and Missouri and have spent time in the woods in Germany (couldn't legally hunt there, but saw some big Red Stag!). Taken deer, hogs, all manner of ducks and geese, and varmints of a couple shades.