15" tire and wheels 65 Barracuda

Have you tried rolling the lip on the fender "very gently" with a wooden block & a small dead blow hammer for a bit more clearance? Just a trick I used with 15 x 8 Centerlines on a B body I had. Just like you, I had maybe 1/4" clearance but afterward I had about 1/2" to 5/8" clearance.