many people take the tunnel. Going around will be at least 100 more miles. And to go around you would have to go through Washington DC and we will never do that again. Traffic around DC is awful!
You will spend more in fuel trying to bypass the tunnel. I would pay the $25-$35 toll. If you haven't already done so, get an I-PASS from Illinois. You can use it all over the northeast. You can go online and add money to the iPass account at any time. Since we have a Class A and toad, we got 2 transponders so we wouldn't have to move one from the RV to the toad. Shield the 2nd transponder with aluminum foil and put in the glove compartment. You can use the iPass to go through the tunnel. You will have to turn off the propane.