A high impact gun should be able to easily shear off the cotter pin. IIRC I was able to reach it with a deep socket on my Ryobi. If not, a 6" extension will provide the necessary clearance.

Of course, the wheel well may not be big enough if your impact is one of these monsters (about 2' long).

 

Work the protruding bits of the cotter pins back and forth with some pliers until the ends break off, then pop a socket and breaker bar on there and it'll twist off no problem. They're soft steel and will easily shear.

 

The original lower ball joints are very high quality and almost never wear out,,

 

The original lower ball joints are very high quality and almost never wear out,,

True, when I replaced my Corolla's ball joints at well over 425K miles, they were still OK.

 

That's good to know! My boots are leaking a little but otherwise the joints are still tight. Impressive for a 20 y.o. car!