On the face of it, of course you're not being unreasonable, and at 16 she should be fine with this.
However, it seems like there is a lot of anxiety on her part, and that's something i can really relate to. I had awful separation anxiety as a child/young adult. It's not something you can control, so the fact that she "should" be fine with this, doesn't magically make it so. This is something you guys need to tackle, as she needs to learn to manage her anxiety and become more confident in these situations. I would really really recommend you both read the book Dare by Barry McDonagh. I had debilitating anxiety for years, and this has been the most helpful thing i have read (it is super accessible and simple, and might help her understand how she is feeling, and feel empowered that she can tackle it, and feel more confident and okay). In terms of next weekend - I would make a plan with her of how she can fill her time, maybe get some nice treats in, help her structure the day and evening a bit, mentally, so she feels prepared and not abandoned and aimless etc. If it would help, maybe have a couple of times when you will check in with her (this isn't ideal of course, and is something you want to work on reducing, but as it's so soon, and she's feeling so uncomfortable about things, it might help provide some comfort and reduce the chance of her calling you etc).
Overall, i think you should go, but do your best to prep your daughter and help her feel safe and confident before hand. oooh and i really recommend rescue remedy for anxiety as well. Maybe it's the placebo affect, but who cares, it does really help with calming. Good luck, and i hope you have a fab day