Is there any way to increase the length of time the screen stays lit/visible to more than 5 seconds?
One option you might try is to use a watch face with the Stopwatch complication. Touch the complication and the Stopwatch app opens. Start the Stopwatch (that makes be giggle a little) and you've got 18-19 seconds of face time. (lol).
This may be less efficient that your current method, but it's an alternative.
Another alternative is to set your Watch to turn on for 70s when you tap the screen, as the prof mentioned. This will eat into your battery life a little, but you can set your screen to 'mute' by covering with your hand or place it against your hip or leg, or whatever's convenient.