My sugardude Wink had severe diabetic neuropathy when I took him in a year ago. I understand and can picture your kitty Larry walking down on his hocks. So maybe try the ear testing first? It takes time to get good at it and for more capillaries to form in the ear and for the ear to "learn to bleed".
I think paw pad testing should be your plan B.
Have you seen all these
Top Ear Testing tips?
Warming the ear, with a rice sock or pill bottle with warm water in it, or by rubbing the ear first, or blowing your warm breath on the ear can all get the blood flowing a bit easier. It will come in time.
If you really, really need to get a drop of blood for testing, like if you think your cat's BG is too low, then aim for the vein. Otherwise, you want to aim for the sweet spot, between that vein and the edge of the ear. Like in this diagram.
p.s. Wink jumps normally now, every where even four feet up to the kitchen counters and mostly walks back on his tip toes. He does walk with a bit of a waddle, especially when he is racing for his dinner. That may partially be because a former owner declawed him. Or could be residual effects from the neuropathy. Just wanted to let you know the neuropathy can get
lots better.