Is it just me?
"not the wireless solution you might hope for"
If you needed wireless to the point of not accommodating a mains cable, surely you'd just lug the source to the screen - in the described case, you could just move your playbook to your tv... in which case a £5 hdmi lead would do the job.
I know that there will be particular use cases for needing in completely wireless, but you need to compromise... I have a use case for a car that will drive for 2000 miles without using any fuel, but it ain't gonna happen!