Guys, It's not like bolting aluminum and iron/steel components together is something new in the automotive world.
Aluminum heads on iron blocks. Aluminum thermostat housings on iron intakes. Aluminum intakes on iron heads. Aluminum transmissions to blocks, aluminum transfer cases to iron transmissions. Aluminum IRS differentials to steel chassis. Aluminum control arms to iron knuckles, etc...Yes there have been issues, but you are making it sound as if components are going to be falling off within a few years...
These trucks are not sitting in a bath of salt water 24/7.
The Ford hood issue turned out to be from iron particles getting on the aluminum panels before they were painted. My friend has a '98 Ranger with a factory aluminum hood. No excess corrosion on it or peeling paint.
1987 Ford Ranger XLT 4x4 2.9
Needs a lot of work, including some rot on the body, but shes getting there.