No, just pull the wheel and the splash shield. There are about five or six 3/8" head screws on the inside. You might have to chip away any dirt, rust or undercoating to find them all. One is located under the hood by the hood hinge.
Once you get the shield out, it's tight, but you can work in there.
Thats a sweet modification. I installed an OEM NOS Ford antenna for a Granada on mine. I wanted the stainless whip style instead of the solid mast style. I like the power antenna idea. I had always dismissed that idea before, because I didn't know how well it would work.
I installed a power antennae on the 66 and had to remove the fender. I could not remove the splash guards from inside the fender well because the screws were installed from the other direction (inside out).