About 120 people have signed the letter so far, organizers said.
James A. LaFleur, PenMar's executive director, said in an interview that negotiations with prospective companies must be kept private until deals are struck.
"You commit to confidentiality with those businesses that you talk with," he said.
Keeping private negotiations secret is a legal and widely accepted practice for government economic development organizations, LaFleur said.
Drastal did not dispute the legality of the private meetings. But he said PenMar has a responsibility to inform the community.
He said he has asked PenMar officials about the companies that they have talked to and other aspects of the redevelopment plan, which calls for turning the property into a center for technology firms and an educational and training retreat.
"The answer that I got was, 'We can't tell you. It's a secret,'" he said. "We don't know if the plan is a workable one."
LaFleur said he has given as much information as possible.
"We've had public briefings that have been very well attended by the community," he said. "We're sharing everything we can with them. I'm the one who instituted the public briefings I don't know how much more open we could be."
Drastal is a member of the Restoration Advisory Board, a group set up by the Army to keep residents informed on issues related to the base's closure and ongoing efforts to remove unexploded ammunition on the property.
Cascade resident Carl Fulmor said the state should set up a similar organization for PenMar.
"They need to be watched just like the Army. They're playing with our dollars," he said.
Cascade resident Robin Biser suggested residents write their own letters to elected officials in order to apply maximum pressure.
"I believe that we absolutely need to be a hemorrhoid," she said.