fix-it-all (joint compound with some additives) is not suitable for exterior at allYes it will wick in water as the paint deteriorates, and cause more rot, and keeping a good coat of paint on it won't be enough long-term in many/most climates.bondo (polyester auto body resin) is a cheap-ish "alternative", although harder to get detail work just right and not really all that suitable anyway (maybe ok with a good epoxy / primer, perhaps?).

Look for BCF nylon or a good PET polyester for stain resistance.Hope that helps.

Polyester Carpets do not wear as well as Nylon, however they are harder to stain.

Microfibres and polyesters clean up better. 

I'm learning towards 18oz of the finest polyester carpet.

Buy white, cotton linens you can bleach (skip the polyester, it doesn’t breathe).

I could barley hear them over their swishing polyester track suits, but they said our last name is almost as Italian as Marco. ; )  All kidding aside thanks for the welcome message.  

When you are buying carpet, polyester is cheaper, but also shows foot wear much faster than nylon.

High cotton content shirt - 100% will wrinkle like hell, but majority polyester or similar holds odors and looks cheap.

PET (polyester) carpets have come a long way, and are excellent for stains, but will show traffic patterns faster than nylon 100% of the time.