Simplest 42.8 MHz generator
Have you seen this chip from Texas Instruments?


  http://www.ti.com/product/cdcs502


The CDCS502 is a crystal clock generator with built-in 4x clock multiplier.

The same 10.7 MHz crystal you mentioned above, plus one of these, will give you a nice stable 42.8MHz clock signal.

It also does spread-spectrum as an added bonus should that interest you at all.