The weight classes are just as you stated "guidelines" but the only time a sanctioned tournament would "have to" follow those guidelines is for qualfying tournaments. For a sanctioned invitational the host could feel free to create entirely new weight groups or combine weight classes as is commonly done.
Kindly review the Kansas Kids Constitution.
SECTION III: TOURNAMENT OPERATIONS
PART A – SANCTIONED FOLKSTYLE TOURNAMENTS
1. All USAWA-Kansas Kids sanctioned tournaments must be sanctioned by USA Wrestling and be on file with the USAW-Kansas Chairman at least thirty (30) days prior to the tournament.
Rule 4-4-1
Competition shall be in the following age and weight classes. Age determination shall be as of midnight, August 31 for that competitive year. For example, a child with a birthday on August 31, 1995 will wrestle as an eleven-year-old during the 2006/07 season. A child born on September 1, 1995 will wrestle as a ten-year-old during the 2006/07 season. Any USAWA-Kansas Kids club may challenge the age of any wrestler during weigh-in at a sanctioned tournament. The wrestler or the wrestler's club must, within one week, provide a birth certificate or similarly reliable verification that the wrestler's age stated on his/her membership card is accurate.
8 & Under
40, 43, 46, 49, 52, 55, 58, 61, 64, 67, 70, 73, 76, 80, 88, 95, 110, 125.
9 & 10
52, 55, 58, 61, 64, 67, 70, 73, 76, 79, 82, 85, 90, 95, 100, 110, 120, 130, 150, 170.
11 & 12
60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 105, 110, 115, 120, 130, 140, 150, 165, 190, 215, 240.
13 & 14
70, 75, 80, 85, 90, 95, 100, 105 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 175, 205, 235, 265.
15 & 16
95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 175, 185, 215, 245, 275.
Additional and/or combined age and weight classes can be used at the option of the host tournament director. 
