https://x-io.co.uk/ngimu/#purchase

I've used these before. They've got quite a selection of neat sensors. If I remember correctly, the only trouble I had was with their little setup/configuration app, but once you know how to do it, you know how to do it. Once you've got it figured out, I'd suggest making a little screen recording and talking yourself through the process then uploading it to your Dropbox or Google Drive so you have it there forever, accessible from anywhere, in case it's a while between times when you use the sensor(s).

NGIMU

 Wow, that looks so interesting. Def buying one to test it out / see how that would work with Izzy.

Hi and thank you for the advice and planning procedure. I'll keep that in mind.
I think I'll go for the NGIMU sensors. A bit expensive, but open and directly hookable to most softwares around. Even being WiFi, your suggestion of using a second computer on/near stage is probably the way to go. I might not even need to control that computer, just having it sending all the data to the FOH and do the rest from there.

G.

Hi, Dont really have experience with those Bluetooth devices, however I do have a lot of experience in theatres. In this particular case, I’d try using a small scale computer on the stage (maybe on the side of the stage or rigged overhead in a portal bridge/flybar/other). This computer would be receiving the Bluetooth data. At the FOH there would be the showcomputer, receiving the data from the stagecomputer over wired CAT.

For monitoring/controlling the stagecomputer remotely, use some kind of remote desktop/screensharing app. I do this with Macs all the time, must be available for Windows too. 

Make sure to test this with an audience in a full house, to see what happens when there are 1000 phones around. Do the test in a non-critical situation. For instance when theres another show on. Check with the theatre and the showcompany if its OK for you to run a test setup during the show. Your showcomputer can be anywhere on the side of the stage as long as its wired to the BT receiving computer. 

Hope this helps. Good luck.