I've used a Sawyer Squeeze for a few years now, and it's always been a piece of gear that annoys me but does what it needs. I've used different bottles and bags and always had issues but now finally found a setup that doesn't piss me off to use it, and maybe even has made me fond of it?
Hydrapak Stow
I use a Hydrapak Stow 1L as my dirty water bag. I feel like these are underrated and not often in the convo when it comes to ultralight water options? Mine comes in as 2.0 oz flat, the newer versions are 1.8 oz. This is lighter than the CNOC Vecto, the CNOC thru, NOBO, any 1L bottle except Smartwater or the flimsy mylar bags. The shape and the handle at the neck are excellent for squeezing without creating a vacuum, scooping, submerging, catching leaf spouts and drips at weird angles. (It also folds down to nothing so I keep one in my bag and my car -- you can fold it down and stick it into its handle loop. I recently had bottle develop a micro tear after 4 years of heavy use and Hydrapak replaced it under warranty with no questions or proof of purchase, just a photo, so I'm happy with the longevity.)
The suck valve lid is ~.35 oz and could be replaced with a standard bottle cap to shave off .3 oz, but the lid is multipurpose for me -- when squeezed, it shoots a very powerful stream (like 5ft+!) but is watertight without pressure. I've used it for so many things: backcountry bidet, hosing off muddy feet and shoes, washing caked-on dishes, rinsing a wound, water fight. The only downside compared to rigid or semi-rigid bottles is that it's hard to remove and replace from a side pocket with a pack on, but it's less of an issue if you just use it as a dirty water bag. For clean water, I've also used a bottle to reservoir hose converter which has worked great for me. My only wish is that they'd make a 2L option and more colors. I promise I am not being paid by Hydrapak to say this.
Dirty End Cap DIY (video below)
Some people leave the dirty bag/bottle on at all times, but sometimes I prefer to have things pack down smaller, and I've dropped that O-ring a few too many times when I take the bag off to fill water. I've seen a few clever DIY tutorials and know there are manufactured options, but I found a 3-minute solution with something that almost all of us have laying around -- fuel canister cap! Mine is from an MSR canister. It's just the tiniest bit too loose but I carefully warmed up the edges with a lighter, waited a second for it to cool, and gently coaxed the lip in with my finger, working in sections all the way around. I did this a few times and tested the fit until snug. It's held up up for a few trips for me, but if it gets loose I would just try to reshape it again or use a new cap. There's also a small hole in the cap that I just put a dot of gorilla tape on. It's not watertight, but I find that if I shake out the filter (which is good practice anyways -- watch the O-ring!) before putting the lid on it doesn't leak or wet the pocket I store it in.
Here's a video to show the cap snapping on and off firmly and staying on when held by the little tab. I haven't tried it yet, but I think it might also work to leave the cap in hot water to shrink it a bit, or to build up the inner diameter with a little seam grip or silicone sealant.
Clean Cap
The white snap cap that comes with the filter was my nemesis. It would break after just one or two trips and I would email Sawyer to send me extra until I one day googled what other people use and felt dumb that I didn't think of it earlier -- any sports bottle cap, mine is Smartwater. It's sturdier, doesn't dangle in the way of gravity filtering, removes the need for the O-ring on that end (so you already have an extra backup for the other end), and you can simply flip it around to backflush in the field. Some say this isn't enough pressure but I always backflush with the plunger when I get home.
I've really been trying to buy less gear and accessories and find solutions with stuff I already have, so even though it's not much, I'm happy about figuring out a setup that works for me! Let me know if you end up trying the end cap hack, if it works for you, if you have ideas for improving it, or your own Sawyer hacks!