Broken Control Arm Bolt

[Sirius-XM]

My 2007 Yaris Sedan fell victim to the dreaded broken control bolt problem. It is way past the extended warranty on both years and miles. It is on the passenger side.

The bolt rotted away at a pretty steep angle allowing me to fit a Flathead screw driver pretty far up into the bushing. Seems with enough torque and the right size screw driver I might be able to get it out. Before I attempt that I was wondering if it was possible to break the bolt loose from the top, making it easier to get the bolt out from below. I took the carpet up and removed the Styrofoam foot rest and there are two plastic covers. Is the top of the bolts under one of them. Does the bolt protrude enough that I could get a vise grip on it to loosen it? What is the proper method for removing those covers?