I've just done three weeks in Japan often roaming about for hours, but in mild temperate weather. I used a lightweight backpack (the sort that folds down into one of its own pockets). The backpack fitted a Lowepro 160AW camera bag (just), a water bottle and whatever other bits and pieces I needed eg map or Lonely Planet type of book, hat, etc. The camera bag had a K-3, FA20-35, FA43, FA77, DA10-17 in it. Yes that all fits in. I had a tripod that I separately strung over my shoulder if heading out later in the day. The weight of all that in a backpack didn't worry me much as it was well distributed across the shoulders. I would have noticed it much more if all that was in a messenger bag as all the weight would be higher on one shoulder near the neck.
I actually bought a smaller tripod while in Japan that weights about a kilo all up and folds down to about 350mm long. It was a Sirui T-005 with C-10X ball head. Not a tripod I'd be using with a heavy telephoto or in a stiff breeze but with the backpack hanging off the centre post, stable enough. Mind you the somewhat larger tripod I was using earlier in the trip struggled with a gusty breeze on top of a mountain in Nagasaki for some night shots so there's always a trade off with tripods that are reasonably compatible with air travel. I've not convinced myself a Gorillapod is all that useful as the likelihood of a convenient rail or post being JUST where you want to take your shots from seems a crap shoot with a high prospect of a loosing hand. And if you do find a rail, other sightseers will have an annoying tendency to bang and bump the rail or a small child is using it for gymnastics practice. Just trying to have no one moving about putting vibrations into viewing platforms or bridges can be frustrating enough.
Vast majority of my photos are done with the FA20-35. The rest of the lenses tend to come out for the walks but don't get used too much. Really most of the extra lenses could stay in the hotel room and maybe one alternate lens would come with me on any given day. Now I have this smaller tripod, I'm contemplating a smaller camera bag with just the camera and the day's walkabout lens mounted on it, the Sirui tripod and maybe one extra lens in its own small hard case. All that hopefully will fit in the afore mentioned backpack which gives good ability to scramble about trails, still easy to manage on public transport but permits evening shots, waterfalls with ND filters etc.
The collapsing backpack is great, if I dont need it, it folds to nothing in the suitcase and adds bugger all to bag weight for air travel. It has a waist strap as well as the shoulder straps so it's quite stable on the back if scrambing about on trails, rocks etc. Messenger bags and normal camera bags will always swing around just when you don't want them to, either crashing into something or potentially throwing you off balance at the wrong moment.
Keeping cool is obviously something that concerns you. While backpacks hold the heat against your back, its the lesser evil if you are expecting to do anything strenous. What I have found great in warm climates is clothing made from 'technical' fabrics that wick perspiration away from the body. Whereas you just end up a sweaty mess with cotton. It's the lightweight clothing you can find in outdoor shops like Columbia, Paddy Palins etc. It also drys real quick if caught in rain or need to do a quick wash back in the hotel at night. I fit myself out entirely with this clothing somedays, right down to underwear. And it packs down much more compactly and lightly in your suitcase/travel pack. If you haven't used this type of clothing before you might be a bit sceptical of its claimed abilities particularly given the premium pricing, but trust me, it works.
Assuming I give into the siren song of the K-1 at some point, I will give the DFA28-105 a good hard look as a travel lens and leave a lot of the other lenses at home. I had a play with this combo in the official Ricoh showroom in Tokyo a few days before the K-1 release and it seems a nice combination. The K-1 plus the 24-70 I think would start to get a bit tiresome on a long day out.
Also if you are heading to Jordan, I imagine the climate on average is dry and there is a tendency for lots of dust and rubbish in the air (ie much like the summers in my corner of Australia). Unless the day is quite still, you'll end up swapping lenses much less than you might expect so as to avoid too many spots ending up on the sensor. Murphy's Law dictates that the only wind gust you've experienced all day stirs up dust right on the middle of a lens change.
---------- Post added 13th May 2016 at 10:08 PM ----------
Oh, one more thing. If you have a preplanned must have vista/ cityscape type of shot, then this web app will allow you to determine exactly what focal length will do the job, showing you what lens is going to be right for the job (allowing you to leave some lenses back home or in the hotel).
ScenePlanner - Tools for camera users
It is quite accurate if you get all the inputs right - I've tested its results against some images I taken myself of the same scene from the same location. Plus it will tell you where the sun is at any given time. Helps you plan what time of day will give the lighting you need. Or preselect a location for a sunset or dawn.