If there is room in a corner of the device you may consider using the Belti antenna. you can free up the ground on the opposite side of the PCB since it is an "on ground" antenna. It is 15.6mm long x4.4mm wide x3.3mm tall and then run the feed into pin 6 on the M20048 module. The antenna performance will be reduced from the advertise antenna efficiency in the datasheet but it should still work. If you would like more help on designing in an FPC antenna please contact our tech support email so that we can receive your design files and review them for the best selection for the best performance with the limited PCB space you have.