Playing “Online Keyholding” with my partner

A couple of weeks ago I had an interesting idea: Before I was together with my girlfriend, I knew about chastity and also online keyholding services. I had never done that, but I remembered its existence these days. The idea of sending the key to a mistress for a week and not being able to get it back, all the while being tasked with various things, sounds arousing to me. Getting kinky messages during the day, having to respond to tasks, matter-of-fact statements of prolonged lock-up.

Since I am happily together with my girlfriend, there is no point to involve a third party into this. So far I have not worn any device for more than a night, and right now I don't even have any device because all prior ones did not fit or broke. The thought of my girlfriend being my online mistress sounds very appealing. This is how I fantasize about this:

Communication would be just via a dedicated chat or letters left in the house. She would not lock me up but rather “send” me an open padlock. At some point after I see the lock, I must directly put on the device and send her a chat message that I have done so. She might reply with some encouraging stuff.

Over the days, I have to report to my “online mistress” via chat. In person we don't talk about the device but she will probably just ask for massages or cuddling because I have signed up with the “online mistress” and there is nothing that she can do about me doing that, right? So just use that I cannot dwell on orgasms and have some romantic time.

The “online mistress” sends me naughty messages and tasks, like having to describe how the chastity makes me feel, or that I have to send her the image from Tumblr that made the cage the tightest.

After a while I am “send” the key for release, then I may take it off and do whatever I like. Or perhaps there are strings attached to the release, I don't know.

The problem is that I don't yet know how to incorporate a couple of activities that I would like to do locked up together with her. Say worshiping her leather without being granted a release. Or pegging. And a tease session with the device on where she feeds me my pre-cum with her leather gloves.

Do you have an idea how this could be combined? Or should it exactly be not combined such that the contrast between in-person and “online mistress” roles can be really high?