Aegismax - NANO2

The obvious is that your sleeping bag is about 2lbs heavier than it needs to be, but replacing it with a decent bag, even a Chinese direct bag like Aegis Max or Ice Flame will consume most of your budget. I assume you're attached to a 2p tent for bringing the little? I've started dreaming about taking my 6yo on trips some day, but I can't imagine asking a kid to sleep under a tarp, (or dealing with a cranky kids who didn't sleep well because he/she was under a tarp) and you probably don't want to invest in 1p tents ... I have experimented with using a poncho as a door (and vestibule) for a tarp or shaped tarp. With the kid, 2 ponchos means 2 doors and the tarp becomes much more of a tent. Ponchos are also lighter than your listed rain gear. If you want to try a tarp and bivvy, oware/bivysack.com has some decent winter sales running right now. Why a puffy and a vest? Is 1 or both of them a layer you could replace with alpha and a wind shirt? Or just a cheap 100 weight fleece? The Dooy Sun Shirt is the current go-to budget windshirt on Amazon. I like mine, though it isn't really tested yet. IMO they fit a half size small, or just a little smaller than an athletic fit, so I happily sized up. There are "reactor" fleece shirts on AliExpress that are just being discussed as a budget alternative to alpha but they're pretty new to the scene I'm also a side sleeper, I can't do just a CCF pad, but I strongly believe much of the hip and shoulder pain actually comes from insufficient pillow. I use about 8 inches of pillow, with one of the tallest inflatable pillows (from Big sky, but there are decent cheap pillows on Amazon), on top of my food bag and other spare stuff. I use a very thin inflatable pad (Klymit x frame) cut to torso length, and 1/8" CCF full length pad under that. Though (in the interest of you budget) I did a proof of concept with the sleepngo inflatable pad that's like $12 cut to torso length.) bears These suggestions are all pretty low on r value.

Aegismax from aliexpress are the best. in the lower price range from my experince,