So, is there any viability to the ridiculous notion that subway tunnels in Brooklyn Heights near the Hillary for America HQ (where John Podesta and Huma Abedin had their offices) can be accessed and used in smuggling/trafficking operations?

Apparently so.

It seems that a couple on 135 Atlantic Avenue in Brooklyn heard tales from a neighbor that there was a secret passageway to an abandoned subway tunnel in their basement.

One night after a few drinks the couple took a sledgehammer to a wall and found two well-preserved spaces of the abandoned Atlantic Avenue Tunnel. After some artful renovations and refurbishing they converted the spaces to a sophisticated speakeasy named Le Boudoir where you can enjoy drinks with clever names like the Guillotine, Air Balloon, Dauphin and Intruder and appetizers and listen to jazz.

http://untappedcities.com/2016/04/05/remnants-of-atlantic-avenue-tunnel-in-le-boudoir-speakeasy-in-brooklyn/

Another article about a Prohibition-era secret restaurant in the same part of Brooklyn Heights.

http://www.brooklyneagle.com/articles/2014/7/30/opinion-real-story-prohibition-brooklyn-heights