Fee

I reguarly open water swim and now I have a 2021 BMW 1 series (my old car was very old so not a concern), no longer feel comfortable leaving my key in my swimming bag on the beach/lakeside. I've looked at a portable key safe but they are very heavy and you need a really big one to fit the BMW key fob in. I've seen how I can separate the manual key and use that to open the car. Could I do this all the time and lock the electronic key fob hidden inside the car? Or would that cause electronic issues if the car knows its manually locked with its electronic key fob inside. It's a bit unclear as videos that show how to separate and use the manual key assume the key fob battery is flat. I also wouldn't want to damage the protective cover on the door handle, so could I leave this off? The manual key is much more hideable and I'm also assuming I could swim with it as it won't mind getting wet?