The problem is going to be the chainguard. Bikes with OEM chainguards are almost always heavy.
Aftermarket chainguards for derailleur systems are very rare. The options for clean running are either a Gates belt drive with Alfine 11 (and some integral chain-tensioning system) or a DIY chainguard made from eg bits of carbon fibre glued together.
The front basket requires flat bars rather than drops so you need the flatbar roadbike style such as Specialized Sirrus, Merida Speeder. I have fitted Rixen and Kaul bolt-on basket brackets and they are lightweight and very strong. I would recommend them over a front rack for lightweight build. Baskets can make the forks flop around when shouldered.
If weight is critical, go for V rather than disc brakes. Beware of brake cables on the underside of the top tube, you want a nice clean underside for shouldering.