This is ass-backwards; to make the required clothing system fit into an arbitrary weight. The way to approach this is to determine what clothing you need to meet the conditions and then, and only then, will you know what it will weigh. What works on a spreadsheet does not necessarily work in the field.
I have seen 24 hour weather predictions calling for highs in the 60's and low's in the 40's turning into high's in the 40's and low's at or below freezing, and this has happened during backpacking trips -- in Southern California.
There is nothing worse, and possibly more critical to your well-being, than windblown rain that is just above the freezing point or even in high 40's F. You can hike in it and stay somewhat warm and somewhat cold at the same time, but when you stop you better have something warm to wear, and sometimes it needs to be put on immediately. Hypothermia is serious business.
In these conditions, if your shelter is your rain gear, you need to have lots of practice on how to set it up quickly, get warm, and not soak your insulation at the same time.
For this reason, I do not have a standard do-all kit. The requirements for each trip often varies. My base weight might be 4 lbs, or it might be 10 lbs or more. And when it comes to weather, you need to be prepared for worse than the forecast.
I do not want to discourage you, just think things out and be prepared. Below is a link to a trip report (remember the audience is my kids) for an XUL trip with temps down to around freezing and rainy days. This was mostly a "what can I do and be comfortable" exercise, not my everyday normal kind of trip. I am no stranger to kits of 5 lbs or less, but they are predicated on the trip, with room for extremes. But the gear I chose for this trip might be helpful. Also remember I have been doing this hiking thing for a long time, and experience plays a big part -- what I am implying is that as the experience level and skill increases, then one can start moving to a more minimalist kit.
A couple notes on this trip...
I brought a Montbell Ex UL vest. It was not warm enough for this trip. However, I planned on using my quilt as camp-wear if needed. But the inner and outer material is completely Cuben, so I was confident I would not get the insulation wet. With a different quilt or sleeping bag, I probably would have brought a warmer jacket.
My poncho is smaller than what most people use. The hiking shorts hung below the bottom of the poncho and sometimes caused me to get colder than I wanted when they got rain-soaked. Since then, I often bring a cuben skirt with this poncho. Hiking with a conventional poncho or something the size of a Gatewood takes some getting used to. Plan on using a draw-cord around your waist for windy days or brushy areas.
Sub 4 lb Base Weight trip