You'd be better of with a NanoPi M4 or T4 or NEO4 than a T3+ for that.
The T3+ isn't very good for desktop use(tablet use). The SoC is a lot less supported than the RK3399's.
With the T3+ you can't watch video in 1080p or higher. It is rather slow for single core tasks. (many tasks are single core)
It is great as server, and for multi-core heavy duty tasks/mining/blender farm. The T3+ is faster than the RK3399's in most multicore tasks, while it has a lower energy consumption.
So the T3+ is very useful, but only for the right tasks.
The T4/M4/NEO4 have got VPU support for 4k video.
The people from FriendlyElec sell touchscreen displays that are supported.https://www.friendlyarm.com/index.php?r ... ry&path=81
Read the wiki for the product to see which boards it supports.http://wiki.friendlyarm.com/wiki/index.php/Main_Page
The M4/NEO4 do have a big and heavy heatsink. Maybe you could make/but a flatter bigger heatsink for it so it doesn't stick out so much.
Most HDMI displays work on the T3+/M4/T4/NEO4. I've got a 7" hdmi display that works fine.
I hope that helps, greetings.