OpenWrt on RBM33G for Bonding (Layer 2)

Good day,

Could someone help me with the following issue or just make a freelancer account and we pay him to do it:

We require an expert to bond interfaces of Mikrotik router with OpenWrt firmware ASAP. The OpenWrt firmware is already installed, and the interfaces are picked up also the load balancing is working perfectly on RBM33G Mikrotik(which has OpenWrt OS) with two Quectel LTE-A cards, and we need to bond the router interfaces together and route all the traffic to one Ethernet. We may also need to do the same thing with other Mikrotik router-boards as well in the future, so we need to know how to configure that router for the layer 2 bonding.
The purpose of that bonding is to have a fast and reliable layer 2 connections between 2 sides. We need a Layer 2 bonding which bond all interfaces through a VPN connection (each interface split the VPN connections) to another server (could be CentOs).
If the VPN connections (For example PPTPs) fails while testing it is not worth of anything.

See the links below for the type of bonding we need:

I can accomplish this task with added hardware, I'll need more details, however I'm under the impression that mikrotik devices do not support onboard openmptcprouter style bonding.

Contact me if you still need the solution.