So, I was assimilating information from these topics:
I started to put my knowledge at work and this is what came out - see attachments.
Basically I can now use my charger of choice and at the same time I can plug in USB stuff.
The small relay inside is switching the power supply for the USB host from the 5V output of the tablet to the main 5V supply when you are plugging in the power adapter (the original or non-original).
The button next to the USB host (I know .. it is white .. but they were not having other colors at the electronics store ) has the function to switch the connection of the USB port from the regular OTG to the circuit that is enabling the AC charging on the tablet. So, when I'm not using the usb host capabilities the tablet will charge in fast mode, with full current.
There is one interesting thing I've found. If I'm plugging in the tablet with the switch in the fast-charge mode and after that I'm switching to USB-Host mode, the tablet will still continue to charge in AC mode (see snapshots for proof ).
I have to mention that all the original functionality of the dock has been preserved and the 30 pin connector at the back can still be used with the original intent (with the proper cables).
If anyone want to replicate this mod and needs additional details, just ask and I'll gladly answer.