My father is a similar situation, long days, maybe one meal (and it's always a bad one)... a while back, I did get him to lose a bit of weight, and as he was pretty damn heavy, it didn't take much change to actually get things going.
1-As his metabolism was pretty tanked from such infrequent eating, I kept him stocked with as many decent tasting protein bars as I could. Since so many of 'em taste like candy bars, but with some protein injected into 'em (and pretty low sugar amounts), he was pretty content snacking on 'em throughout his work day.
2-Made him eat breakfast. it wasn't always a big deal, but a shake and a banana can be a hell of a step up from nothing.
3-dinner was always 'healthy'. Usually a lean protein source and veggies. If he wanted a snack, it'd be nuts or peanut butter.
4-A very sendentary indivual, my Dad was actually able to make noticeable progress from a simple 45 mins 'workout' (basic weight work, and 20 mins walking on a treadmill) done 3-4x/week.
A lot of the 'sports supplement' market is geared towards the average joe these days, and as such, he can enjoy what seems like candy bars, tasty shakes, even protein peanut butter and protein pudding. Basically, I'm thinking that the biggest area to focus on might be simply establishing a better eating cadence, and let his better adapt to using the incoming nutrients more.
Good Luck, I've been there (and still get frustrated as hell with my ol' man).