Nope, a liquid yeast wouldn't be too much. I don't know off the top of my head what the conversion would be from the "commercial pitching rate" is for a one gallon batch, but I do know that a vial of White Labs or a packet of Wyeast wouldn't be too much.
Just make sure you use a blowoff. Many of the wheat yeasts really get after it.
FYI, most dry yeast packets have a much higher cell count than the liquid yeasts.