Brick Walls - Theoretical Limit

So, apparently, most of the data of interest that can be collected from a wind-tunnel is going to be governed by the Reynolds number, not the freestream speed. Consequently, I need to design my wind tunnel to maximize the Reynolds number. Not only does the tunnel need to be designed to maximize the Reynolds number, the model does, as well. The Reynolds number (Re) is proportional to the length along the aerodynamic body. If your aerodynamic body is 1/20th the size of the 'real thing', then you have to up the other components of the Re by a factor of 20 to compensate...That puts the theoretical max for my toy truck's simulated speed at about 15 mi/hr...