Welcome to the forum!
I don't think we're getting bad economy in our auto. We just did a trip with some of the local guys and returned 10.46LPHK for the entire journey, a small percentage was city driving, most of it was highway, and we are loaded up somewhere just over the 2.5T mark (if I had to take a good guess, I'd say around 2.6T). My car weighed 2500Kg coming empty out of the local tip, and it's now got our Engel 60L chest fridge, the deep cycle battery, Honda EU20si genny, tools, stoves, picnic gear, folding chairs etc in it.
If you are going to tow, I wouldn't attempt convincing you to get the manual. Riding the clutch to get moving is a killer that (like all failures) strikes when it's most inconvenient. You don't get that with the auto - but I would caution you to be less enthusiastic with powering off from a stop, or climbing hills, on a very hot day. The auto has an oil cooler but it still has its limits.
Last Christmas we were traveling up the Silver City Highway towards Broken Hill and on one of the rises I put my foot down (this was middle-of-the-day stuff, aircon going flat out as well). The temp started to rise rapidly - I backed off and everything went back to normal.
Drive it in a reasonable manner and it will do you very well. Congratulations on your purchase, too!