My only concern is the RTT will be right over top of that - so if a bear does decide to go after food - it's right underneath me.
That was my concern too. So I treat the truck bed like the tent, no food and nothing allowed there that has hand odors.
The refrigerator is in the back of the cab and not removable without tools so I put my food bin and garbage bag in there with it. Windows and doors closed to help keep scents from getting out. Most garbage is in the emptied out ziplock bags I brought the food in. Kitchen goods and stove are cleaned but just in case they're kept away from the RTT (usually on a picnic table if I'm at a site). Washwater and any food scraps/grease that aren't in the garbage are usually poured into the firepit before making a fire. If no fire then they're dumped out far from camp. Same with "human" waste issues, also taken care of 100ft or more from camp.
Basically by time I'm going to bed at night any food or odorous object is packed in bins and those bins sealed up in the cab if the site doesn't have a bear box. Not even crumbs are left on the ground, any dropped food is incinerated.
But in nearly 40 years camping bears have never really been a problem. It's the smaller creatures that are really a pain. I've had coyotes chewing up plastic containers, chipmunks and mice eating through cardboard, and skunks walking around camp like they own the place. I think the best solution is just good general cleanliness of camp. Make sure your neighbors smell more delicious than you do and your camp has no odors that aren't natural odors that exist before you were there.
It's the old rule of surviving a bear chasing you, just surround yourself with people slower than you. Or a better way of putting it, don't make yourself a target in the first place.