It's a word-name to me...all I can picture is a teenager calling for her beau (boyfriend). In my opinion, it's a rediculous first name, even as a nn.
Beauregard is a bit much for me, but I don't hate it. I just worry knowing the most likely nn is
Beau and then were back at the beginning of this paragraph.
But as a mn, if you can find the right combo, I think
Beauregard would be wondrful.