IMO I do think Captain America makes some sense for a coaster at DCA. Mainly because
1) In the time period of DCA, which is mostly the 1940s besides Bug's Land and Cars Land, Captain America makes more sense to have a ride than Iron Man. If anything, I'd say an Iron Man ride should be part of a TL overhaul.
2) If it uses a ride system similar to Tron in Shanghai, instead of being a light cycle it could be a motorcycle and you could be joining Cap and his commandos on a mission.