How can I split files on the computer and then assemble them on android device? Would be a simple way to bypass the MTP protocol crap to transfer files to my android tablet. There must be app out there that I can split files in pieces on computer and then reassemble on android device.

Any suggestions?
If you're able to transfer the split files from your pc to your android device, which most probably will, you can use this app to join the files. 

Also make sure you split the file using 7zip on your pc.

Hope this helps