Case closed! (seewhatIdidthere?)
Ended up with a PD Everyday Backpack 30L, thanks @Carbonman! It allows me to have both cameras with their respective lenses mounted accessible from the same flap, and still have enough room for the other lenses with leftover space for a light poncho, snack, etc. I could actually still get a couple more lenses in if I wanted to, or the 500/8 AF. I like the fact that the waist belt is optional as I don't need one for this use. The sternum strap can be stored on one of the shoulder straps, again, I won't need it. The shoulder straps are compact and have magnets to hold them snug against the bag so they're out of the way when carrying by the handles. It's a lot thinner in use, especially with the straps as described. And it's about 2-1/2lbs. lighter. Drawback is it's expensive. I'm pretty sure I own a 51% share of Peak Design at this point...
Ended up with a PD Everyday Backpack 30L, thanks @Carbonman! It allows me to have both cameras with their respective lenses mounted accessible from the same flap, and still have enough room for the other lenses with leftover space for a light poncho, snack, etc. I could actually still get a couple more lenses in if I wanted to, or the 500/8 AF. I like the fact that the waist belt is optional as I don't need one for this use. The sternum strap can be stored on one of the shoulder straps, again, I won't need it. The shoulder straps are compact and have magnets to hold them snug against the bag so they're out of the way when carrying by the handles. It's a lot thinner in use, especially with the straps as described. And it's about 2-1/2lbs. lighter. Drawback is it's expensive. I'm pretty sure I own a 51% share of Peak Design at this point...