"As mentioned above, I'm considering adding a plate to cover the t-case access hole."
With all that protection, you would be remiss to not make a cover plate...drill or torch a 3/8" hole on either side of the rectangular hole, weld a couple nuts on the top side of the "belly pan", and bolt thru from underneath.
Easy drop down , or swivel aside action for maintenance. This type of "belly pan" was quite common on the Caterpillar dozers, loaders, and scrapers I used to work on as a kid.
Except they used 3/8" plate

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Great job on your "belly pan".
One suggestion...you might consider welding an angled edge on the rear, so if you ever find yourself reversing out of the rocks, you won't catch on the rocks, but will ramp up over them.
Consider posting the dimensions for tech.
Way to go!