I just got my Tenba mini Shootout yesterday and I've figured out that I can get the following into it:
K20D with Sigma 17-70 attached
DA55-300
1.7x TC
DFA100
Sunpak 383 flash with StoFen diffuser attached
K55/1.8
M28/3.5
FA43
second body (either film or digital) without lens attached
Judging by the gear you've listed, I don't think you'll have a problem fitting all of it into the mini backpack.
Tenba does offer an attachment that goes on the outside and will hold a bottle of water. Since the mini doesn't have a waist strap, I'm not sure how the water bottle holder would work with it.
Tenba - Shootout: Lens/Bottle Caddy
Looking at the specs on Tenba's website, the mini is rated to hold 2 bodies + 4-6 lenses and the small is rated to hold 2 bodies + 5-7 lenses, so it's a little bit bigger.
As I was getting my new mini set up, I also strapped my tripod (BM 190XPROB + BM486RC2 head) onto the back to see how it would work. It fit fine, but the mini wouldn't have worked too well if it had been much bigger. With the bag loaded and the tripod strapped on, I put it on my back and while it was heavy, I think I can still manage it for longer hikes (I'll most likely get a photo vest and tripod strap for shorter hikes). Sizewise, I think it will fit into the overhead compartment of a regional jet, so I don't expect there to be any issues with me carrying the bag onto any plane, unlike with the medium rolling Shootout backpack that I did have.
HTH,
Heather