I try to see what purpose this coin can fill. Seem very limited at 128kb
The data transport mechanics are up to you.
If you want to send a megabyte in 8 parts, then you segment the payload into 128KiB sized pieces and write it to the chain.
After it has been enscribed, then the chunks may be re-assembled into their more useful format.
Small TX limits are helpful to promote swift propagation throughout the network.
Best Regards,
-Chicago