Anybody know what the quality of replacement front fenders from say LMCTRUCK are like? Thinner metal than factory? Can't find one around here that doesn't have rust issue.

 

Can't say for sure about LMC in particular, but for the most part, all the aftermarket body panels are not up to Ford's original equipment standards. I'm in Ontario so I feel your pain with the rust issue.
Keep shopping around though - they are out there. I've bought $500 POS trucks with bad brakes, rusted lines, exhaust falling off, and perfect fenders. Pull the parts you want and the scrapyard will still give you 3 to 400 for the rest. $100 fenders. That approach worked for me anyway