I've managed to connect the Asus Transformer T300Chi; this may work for other tablets/hybrids/modern Bluetooth devices.

I am working from the 16.04 GUI installer in 'Try' mode. Touch-screen and stylus input was working so I first went to System Settings > Universal Access and enabled the on-screen keyboard.

Then I was able to join to the WiFi network by entering its details. With that I opened a Terminal and installed the SSH server with:

$ sudo apt install openssh-server

I then set a default password for the 'ubuntu' user:

$ passwd

And then from another PC was able to ssh to the T300Chi:

$ ssh ubuntu@10.254.1.42

With shell access I then put the docking keyboard into pairing mode and did: 

ubuntu@ubuntu:~$ bluetoothctl
[NEW] Controller 34:02:86:FC:AD:59 ubuntu [default]
[NEW] Device 1C:B7:2C:04:C7:FE ASUS T300CHI DOCKING
[bluetooth]# agent on
Agent registered
[bluetooth]# default-agent
Default agent request successful
[bluetooth]# scan on
Discovery started
[CHG] Controller 34:02:86:FC:AD:59 Discovering: yes
[NEW] Device 00:1F:3A:E0:0A:AF hephaestion.lan.iam.tj
[CHG] Device 1C:B7:2C:04:C7:FE RSSI: -36

[bluetooth]# pair 1C:B7:2C:04:C7:FE                                                                                                                           
Attempting to pair with 1C:B7:2C:04:C7:FE
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[agent] PIN code: 117372

At this point I typed the PIN code on the docking keyboard followed by Enter.

[CHG] Device 1C:B7:2C:04:C7:FE Modalias: usb:v0B05p8502d0001
[CHG] Device 1C:B7:2C:04:C7:FE UUIDs: 00001000-0000-1000-8000-00805f9b34fb
[CHG] Device 1C:B7:2C:04:C7:FE UUIDs: 00001124-0000-1000-8000-00805f9b34fb
[CHG] Device 1C:B7:2C:04:C7:FE UUIDs: 00001200-0000-1000-8000-00805f9b34fb
[CHG] Device 1C:B7:2C:04:C7:FE Paired: yes
Pairing successful

I then started pressing keys on the keyboard which caused lots of messages

[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Class: 0x0005c0
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Icon is nil
Authorize service
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Class: 0x0025c0
[CHG] Device 1C:B7:2C:04:C7:FE Icon is nil
[CHG] Device 1C:B7:2C:04:C7:FE Class: 0x0005c0
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Icon is nil
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Connected: no
[CHG] Device 1C:B7:2C:04:C7:FE Class: 0x0025c0
[CHG] Device 1C:B7:2C:04:C7:FE Icon is nil
Request canceled
[CHG] Device 1C:B7:2C:04:C7:FE Class: 0x0005c0
[CHG] Device 1C:B7:2C:04:C7:FE Connected: yes
[CHG] Device 1C:B7:2C:04:C7:FE Icon is nil

Until I noticed the following message and prompt

Authorize service
[agent] Authorize service 00001124-0000-1000-8000-00805f9b34fb (yes/no): yes

At which point the docking keyboard and trackpad began working:

[ASUS T300CHI DOCKING]# paired-devices
Device 1C:B7:2C:04:C7:FE ASUS T300CHI DOCKING