Well I don't think you would want to be lugging around a lan box filled with watercooling gear in it.. I mean I know its probably fine but I wouldn't want a w/c rig sitting in my car.
I know this case would fit the cards with space for the cards and honestly unless you seriously want to consider investing $300 worth of watercooling gear OR can return the cards for the blower style reference coolers (which in your situtation would cool better then the cards you have now but will be probably be just as loud with just a little two slots of space your cards will always be whisper quiet until 70% fan speed.
I don't want to say what other people are telling you but I highly doubt this is a issue with the card itself, re applying better TIM would most likely give some small difference in temps, but nothing to a acceptable range. Before I bought a switch 810 full tower i used a mid tower for two SLI video cards with no space in between. I had to set the fan speed to the top card at 70% BEFORE I started gaming so it could keep up, if the curve adjusted after it got hot the card would sit at 85c-90c. Never reaches above 70c in its current configuration with two slots of space between.
I would test the cards in a benchmark or game that will heat em up quickly... set the fan speeds to a high % and see if it rises fast or not..