I feel your pain, in my shoulders, back, and bruised side where I laid against the edge of the cabinet base.
Just replaced our kitchen faucet too last week. Didn't know if I was going to get that nut loose or not, but finally did. The new faucet came with a little tool to get the new one on, so next time should be easier as long as I don't lose that tool.
Also on Monday just replaced 3 bathroom faucets and the innards of all three toilets 2 weeks ago. I hope I'm good for awhile now.
I always lay on the ironing board pushed into the cabinet. It certainly helps!
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