The BH-40 is actually pretty low profile. Excellent for traveling. I really love the Markins as well but it is a little taller if the length is super critical.
I had an RRS BH-25 that I kept on a monopod in my truck. I usually only used it with an older D70 / 28-200mm that I kept in the truck for those moments when something popped up and I didn't have my other gear with me.
I tried the BH-25 a little while ago on a set of legs with the D200 and 70-200mm VR. It actually worked pretty good. I know that is more than what should probably be done on that head but I was just curious since you asked. I am not saying rush out and do it but I do think RRS is probably a little conservative on their weight ratings. For a low profile head, the BH-40 would still be best but you might be fine with the BH-25 for just occasional use when you were trying to fit something small in the suitcase.