It’s just my opinion, but I think you’d be stretching the limits of bluetooth at 50’. A lot  will depend on the quality of the BT transmitter you select.  I would guess that having a lot of people in the space between  the projector and speakers is going to have a negative impact, similar to what we see with WiFi.  But I am mostly guessing.  I have seen bluetooth work well at 50’ in an office setting, so I could be off on this.

As an alternative, I would look at just going the traditional route and using a long run of outdoor rated speaker wire.  You could use a Sonos amp, or really any amp if it doesn’t need to be part of your larger system to power some decent outdoor speakers.  Yes, you may have a tripping concern with the wiring, but hopefully you can work around that.

I’d recommend traditional speakers for that venue. Don’t purchase a MOVE for this. For items listed in your profile test with a pair of FIVE’s up front. Of course, you’ll need something with Line-In near the projector. In any case voice sync will suffer.

The biggest issue here is the fact that Sonos indoor speakers are not designed for what you are trying to achieve. Even if you are able to overcome the lip sync issue because of the 75ms delay when using line in, the speakers are simply not powerful enough for an outdoor environment.

If a Play 5 doesn’t provide the audio you are looking for, as ​@melvimbe suggested, an Amp with a pair of good speakers in front may be a better option for you.

Thanks everyone, you fine folks are trying to persuade me to NOT add to my Sonos collection :-(

As this is for occasional use only, I though a Move would be a fine solution, the rest of the time I have much saner plans for it.

The 75ms delay was not a problem with the P5, so I’m not expecting it to be for the Move.

I have a BTA 30 Pro (as previously recommended on this forum) connected to a Sonos Port in a cabinet inside house, I can just about get 50’ range outside, through a brick wall, to my BT headphones. If the BT transmitter has clear line of sight, I would assume 50’ would be achievable to the Move. This site suggests range doubles outside:

https://www.bluetooth.com/learn-about-bluetooth/key-attributes/range/#estimator

I agree, having people in path of the BT signal will impact, but could mount the transmitter and speaker higher?

Hey, my suggestion of the traditional route could be done with all Sonos speakers, but it is overkill for what you’re trying to achieve I think.  

I also think the 75 ms delay wouldn’t be a big problem in your use case.  I have connected  sonos to TVs via bluetooth before and didn’t really see a lip sync problem. 

I bet the neighbour whose external wall you’re projecting onto is pleased this is only occasional, given the volume you’re wanting to achieve…!

Sometimes the source lip sync is so poor that an additional 75ms delay is constructive.

She is in the audience along with many other neighbors!

Thanks I might try this. The PJ is on the upper floor, so has a clear line of sight to any speaker, no water bags (ie humans) in the way.

She’s not got much choice!!