I ride 48/16 with 170mm cranks and standard road wheels/tires. That works out to 79.1 gear-inches. It is very hilly here in North Georgia. I am 52 years old and in decent shape. The bike is 8.3kg.

5% grade is tough for me. If the hill is short enough I can spin up and over but if it is longer then I have to stand and work hard to keep the cadence up. 5% for a half mile would really hurt. I try to avoid anything beyond 6%. With anything 4% or below it isn't so much the grade but the length of the climb.

Real road bike bars with proper brake hoods help tremendously. The droopy pista bars were the second thing I changed on my bike after the saddle.

Keep in mind that your 49/18 with the same cranks, wheels and tires is 71.8 gear inches, a bit lower geared, and so things will likely be easier for you. The advise to go out and try is wise. A million people telling you things on the internet won't give you as much information as riding up one hill.