I think you can do it without too much duplication. As long as you have two baselayers, one of everything else should be fine. Your biggest decision will be waterproof (paramo vs other). At the moment seems to me that the best "other" would be neoshell (for that length of time event would need many reproofs and gore active shell would rip). People will give you advice either way but personally I prefer paramo velez trousers and a non-paramo jacket (when it might rain it's never been too warm for paramo trousers with venting open) but lots of time when it may rain a paramo jacket is too warm in summer.
You'll need another pair of trousers, personally I'd go for a softshell e.g. powershield (not windstopper whatever you do) for warmer weather with light rain possible and a pair of shorts.
Baselayer is up to you, can't say I notice any difference from any of mine (icebreaker, polypro, polyester) but then I haven't tried the latest meco or arcteryx (and don't intend to as can't afford another top for only incremental improvement.
Mid-layers personally I use 2: powerdry and powerstretch layered as necessary. Don't get a full weight fleece as for real warmth you'll get better use out of synthetic (don't get down for that length of time). If sitting around in evenings you'll probably want at least 133g/m2 thickness (but likely more). I'd get the more by layering a synthetic gillet with a synthetic belay jacket for more flexibility.
Finally a thin pertex windjacket (many available, no real difference but you'll want microlight not quantum for that length of time).
Only other thing to note is don't wear normal cotton underwear, saying above that I don't notice the difference between different baselayers, I really do notice the downside to cotton underwear (gets damp, stays damp, then rubs) many options available.
Sorry but all of that's around 1000pounds. Notice that I haven't listed specific products as I don't think any one brand is really much better than another, fit is far more important. I've also not made it ultralight but have cut down to allow you to wash one set whilst wearing another.
Be interesting to see other opinions though.