Cockpit improvement

I don't think this is true - are you 100%? Pretty much every modern carbon fork will take a 25c and a lot would take a very tightly squeezed 28c (which I wouldn't suggest tho). From the ones I've seen on my commute they'd also take a 28c rear.

My vote would be for 25c tyres, checking your bike is set up correctly (including installing two proper drop brake hood leavers) then possibly carbon bars, and if you want to drop weight a lighter alu stem with ti bolts. When i was looking Deda and Ritchy were the best option for weight and price.

I am going for Crud Road Racer mudguards so I can go up to 23 front and 25 rear tyres. Yes, before I was running marathon + 25 tyres and was really comfy but during the very cold days of winter I was getting plenty of rust on some parts of the bike from the salt so I had to use mudguards.