I don't have any
template advice, unfortunately; I just have some advice regarding determining placement and how many of the belts of each type to make. The theater I am currently working with had a party this season consisting of the sound engineer, costume shop manager and wardrobe supervisor in which they remade quite a few of the Mic belts. The first thing the sound engineer did was to create a wooden mock up the wireless pack they are using to make sure the pouch for it was of the correct size; not good, even if you put some form of top
safety catch on it, if the pack is able to move excessively within the pouch. How she has also handled the question of where to put the mic pack is actually very simple. She gives
stage management a sheet and asks them to have all actors note preferred placement of the pack at either waist, bra, back or other. The actors know their
blocking and choreography (or at least they should have some idea of it). She then goes to the costume shop to confirm that the placement will work based on each actor's costume, and to get the measurements of each actor. This allowed her to accurately
gauge how many of each belt she had to make (or modify).
I'd caution about being dictatorial with placements of the packs. Underarm may make sense to you because it is out of the way; to the men in the cast it might just prove annoying to have it there. Maybe, though, they won't care. By working with the actors and costume shop to determine placement (I know time is short, but it is the same here as well), you'll make sure the cast is happy and have a better chance of not crushing a pack or ripping the mic
wire out of one in the middle of the show. Working with the costume shop will also allow you to possibly get some of the measurements you will need, like chest size. You may also need to go and get some thigh sizes if you go the route of thigh placement. Especially on the legs in a dance show, if it is too tight or too loose you will have same major issues with either the actor being extremely unhappy or your pack going flying (which would likely annoy the actor as well).