Old faucet has flat mounting nuts - how to remove?

[Fragille Bill]

My bathroom faucet is a Delta/Delex widespread installed in the late 70's (photo attached). It works fine but I would like to replace it if I can remove it. The issue is the hexagonal mounting nuts on the underside. They are almost flat, no more than 1/8 of an inch deep (photo attached). There is very little edge to grab with a basin wrench or any other type of wrench. I'm guessing they were installed with a special wrench that came with the faucet. I have not started the project yet and want to be reasonably sure I can remove the nuts before I start. Does anyone on this forum have experience removing mounting nuts such as these? If so, what wrench did you use? Thank you!

 

[breplum]

Haha, I remember thinking "what a piss-poor design" when they came out.
I think that faucet came with a thin metal fixed opening basin type wrench. It was crap to use.

 

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[Fragille Bill]

Haha, I remember thinking "what a piss-poor design" when they came out.
I think that faucet came with a thin metal fixed opening basin type wrench. It was crap to use.

That's what I figured. I sent this question to Delta a couple days ago but have not yet received a response. I've seen a Husky adjustable plumbers' wrench that might work, but I can't try the wrench without removing the copper tubing supply lines first. Maybe I could get it out from the top with an angle grinder.