Could I walk 400 miles to my bug out location?

Probably. If I was with wife only, not toting the two cats, minimal loads and I was prepared to move at night, hide during the day, beg/borrow/steal what I needed - basically what I did back in the day in what was then SERE school.

Is it feasible? Not unless I absolutely had to. As in, the zombies have overrun my town and/or the baddies have announced plans to nuke my area.

The best scenario is I determine it is time to beat feet well before the event happens. I load the SUV with stuff and leave off to the safe point. If nothing happens, oh well, good training for when it does. If the fecal matter hits the rotary air impeller, good for me for not being in the general area.