I'm gonna issue an ultimatum, backed up by absolutely nothing: desert boots = sneakers, basically. They're a bit more elegant, but wearing them with a suit is about on par with wearing sneakers with a suit. I wouldn't do either with seersucker. I have done both with a tan poplin suit (brown shoes, though), but I'm an art student wearing a suit when none is needed, so I can do whatever I want.
Bottom line: the most tasteful choice for a shoe to wear with seersucker would be bucks. The most tasteful use for those shoes (in khaki) would be chinos and a polo or madras shirt.