That's the thing, there is no way to properly do the bonding.
Bonding occurs at the source, not the load. Your house, for example, had the neutral and ground bonded at the main fuse box and then subsequent sub panels are not bonded (by code). Outlet boxes do not bond N and G and loads/appliances do not bond N and G. When you bond neutral to ground at a load or downline from the main bonding point this creates ground loops and is against code.
The inverter you want to use specifically tells you not to bond either of the outputs to ground and as such cannot be "properly" used as a source in a house, it's fine for running stuff while camping or at the beach. That's likely why it was so cheap.
It sounds like you don't have enough money to do this properly so you keep asking new questions hoping for a solution that doesn't require you to spend more but the simple truth is that the source neutral needs to be bonded to ground and the cheap Chinese inverter you bought with no UL approval specifically tells you not to do this.
You've made a mistake and bought the wrong inverter, trying to make it work anyways could just compound the mistake from one to two or more mistakes. It sucks when you make a mistake that costs you money but the smart thing to do now is sell this inverter and get one with a UL approval that alllows N to G bonding.