you shoudl be fine.
even driving through standing water at high speeds the water isnt going to splash forward and defy the laws of physics and make its way into the filter, maybe a few drops will splash onto the filter but you would have to submerge the whole filter in water for the motor to hydrolock.
if youre really paranoid, fabricate some sort of splash guard that fits under the filter, so any water splashing from below hits that piece. you can get sheetmetal and brackets at home depot, take off the fender and fab something up for a few bucks.
IMO i wouldnt worry about it unless you drive through 1 feet of standing water on a daily basis. if the water is that deep to get sucked into your filter at 2mph that is at least 2' above the waterline at all times, you shouldnt be driving through it.