I grew up where the canal holiday industry was a big employer. Quite a lot of the staff used to work on towed barges in their young day. Legging is definitely how they got through tunnels. Barge poles are used to fend off after being moored up or to prevent collisions in narrow stretches. Once the barge was out the tunnel they’d throw a line to someone on the towpath and hitch back on to the horses.
Not sure that its a must have and possibly uBO could handle it if I could be bothered to check but I like LocalCDN too.