since the lower is rusty, it would make sense to go lighter like a toupe or kahki colour. Your thoughts?

 

if you're having rust problems, use a spray on bedliner (rhino liner, herculiner, raptor liner) to prevent the spread. a lighter color might look better, but the rust will eventually just eat it away too. the bed liner is wayyyy easier to prep for and apply as well

 

+1 you could paint it but the rust would eventually eat away at it.