If you don't get a response here, try sending email the White Clay Bicycle Club in DE at
info@whiteclaybicycleclub.org. I did one of their rides years ago, they can probably give you accurate info. I'm pretty sure the St. Georges bridge (Rt. 13) is still fine - the car lanes were reduced from 4-2 and the bike lanes put in years ago, but I don't know the current condition or what the Chesapeeake City/213 bridge is like - the White Clay folks should have better info.