The 25 buck Sawyer mini is a good choice- just don't let it freeze, I keep mine in a pocket. Saves you from boiling water to drink, and allows for filling up in a puddle that's 3" deep. I use a 2 liter Evernew as a "dirty bag", instead of the small one supplied with the filter. Bring a paper coffee filter to take out the big stuff like leaf matter. Unless I'm in the desert somewhere or forced to dry camp, I rarely carry more than 2 quarts. Tarps are useful and cheap, but I've spent too many nights getting spindrift, dust, sand and sideways rain on me. Did it for years. Blue tarps aren't light, they weigh almost as much as a tent (near 2 lbs.). By the time you add some mesh for mosquitos, guylines and stakes, you're still cheap , but not that protected and getting on the heavy side. Tents will also add warmth when its chill. Sil-nylon tarps are lighter and far stronger. Blue tarps SHRED in heavy wind. I've been a builder and using them for 40 years, they will not withstand wind over 30. My wife put her foot down long ago- No tarps! They're the same material as you find in garbage Wal-Mart tents. The same ones you find filling dumpsters in campgrounds after storms. I often bring a 6 by 8 sil-nylon tarp for a cooking shelter when we expect rain. I pay the 1 lb. penalty for the luxury of having it. The tent you have is heavy, but you can put it in another perspective if you like it and don't wish to upgrade. Shelter weight is divided by the number of people using it. With that formula, you're significant other gets half the weight like the fly and poles, leaving you with 2 1/4 lbs. in your pack, rather than the full weight. When we brought our Lab, may she rest in peace, I found tarp camping was out, as she would get up and investigate noises in the night and I'd constantly be calling and fussing after her. When she was semi-enclosed in a vestibule or lying between/on us, she'd settle in and be far less inclined to chase the noises and smells of the night.
The Sawyer suggestion can save you some real weight. If you aren't carrying an extra 2 qts. of water, that's 4 lbs less- basically the same as buying a Cuben Fiber shelter as a tent replacement that will go north of 800 bucks. Food is another heavy item- look at it closely and you can pare some weight there, too. Clothes also can add tons of excess weight. You need enough to keep you warm and dry, not enough to keep you sweating from carrying them around!
Until I was 50, I carried a 90 liter pack, often with full SLR camera gear and a tripod. fishing equipment, and lots of luxury items. You do sound as if you're very active and healthy. That's a great, great thing; IMO, fitness will outdo weight savings by a long shot. That's not to say some weight savings won't make things more enjoyable and help you go farther.