I would first start with an energy audit ... and decide what exactly you plan on running when the power goes out.
Then I would look into cobra 12vdc 1000w inverters when you realize all you will be able to run is your fridge for a couple hours and some LED lights
You car can keep you powered likely longer than your bike could.
On another note if you get 12v LED lights you can simply run them right off the bikes
DC:DC 300w converter ... 300w is a lot of LED light. My shop lighting in the garage is 35w and it is shocking how bright it is.
Other things to consider (if your taking this seriously)
Do you have a blackout kit in several locations in the house, and does all the family know where they are? (I like the lights you plug into sockets and when the power goes out they turn on for intermediates to safely get to your blackout kits)
Do you have a 72 hour kit for every member in the family?
How will you take care of waste if the sewage system goes down?
Do you have an extended pantry and if so how long would it last if you were trapped at home?
Do you have a binder at home and in your vehicles which show escape and meeting points if your family has to get out of their house for any reason?
Do you already have a chest freezer you have filled the bottom with water bottles in case there is an outage?
Do you have a chest freezer you converted to a fridge because it is like 10x more efficient than your fridge?
Do you have water stored up and a way to filter water if you need to? (5 gallons a day per person is the average amount of use)
Do you have a method of cooking / heating food without using a microwave or electric range oven?
Do you have a method of saying warm / cool?
Do you have policies and procedures in place for if the power goes out and have you trained everyone in the family on how to safely use the inverter (I know you don't have it yet but seriously think about this as you might not always be around and or able to assist and someone could get hurt or make things worse)
You have opened Pandora's box my friend
The key is not to freak out over any holes in your plan (assuming your taking this seriously) I might have uncovered. Think it through and make a plan while crossing it off
I am sure I missed some things but you get the idea.