Ask one of your local Leos. I'm not familiar with Missouri codes, but in Texas, obstructing the license plate with a bicycle rack is not a violation.
Found this on their DMV site: "If a rear Missouri license plate is obstructed from view by a bicycle rack, luggage rack, or other similar device, the vehicle owner has the option to obtain a Temporary Third License Plate. This "third license plate" is printed on 8½" x 11" non-secure white paper and will contain the same license plate configuration and expiration date as the permanent license plate assigned to the motor vehicle. It is to be placed in the interior of the vehicle’s rear window such that the driver’s view out of the rear vehicle is not obstructed and the plate configuration is clearly visible from the outside of the vehicle."
I can't find anything about a front plate only vehicle. Except that a single plate is issued to a commercial vehicle over 12k gross weight.
License plates, required slogan and information — special plates — plates, how displayed — tabs to be used — rulemaking authority, procedure.
revisor.mo.gov