thanks @Pyk_ figured someone would link the datasheet.
the FR4 plate in the picture is 1.55mm
if there are any connectors, JST, 3.5mm trrs, socketed promicro, etc... you're going to need a minimum of 5mm under the bottom plane of the pcb to clear those components. not sure if your using an official alice pcb or not. if you are, look at the pcb and get spec sheets for the components (if you don't have the pcb)digikey & mouser usually have spec/data sheets on almost everything.
not sure where you're located, but the calipers i used are just a cheap set off of amazon (less than $20)