I was going through the checklist PDF provided by Hayward city (https://www.hayward-ca.gov/services/permits/accessory-dwelling-unit) and one of the requirement says Are you the property owner and do you reside on the property?

If the latter, could you build something with a suite or accessory unit thereby increasing the rental income or even resale potential? 

We have a legal accessory apartment that we currently rent out, however, as far as I can tell, we would be in violation of the zoning commission if we were to move and rent the main section as well.

People go back up north when it gets so hot.One thing to explore and is an idea that is rocking right now in LA is the concept of an ADU [accessory dwelling unit] or guest units, people are adding guest units and doing ADu conversions - this allows you to take a SFR and add or convert it to a legal rental, as opposed to having to rent out an extra bedroom and deal with roommates, you can take that same bedroom and add a kitchen and bath and you have an ADU that can rent out for a premium.

Is it big enough that you could build a small accessory dwelling on the lot and rent it out?

We have a legal accessory apartment that we currently rent out, however, as far as I can tell, we would be in violation of the zoning commission if we were to move and rent the main section as well.

and build an accessory dwelling unit (ADU) on  Prop 2 which would generate about $2400/month gross rental income, bringing that property's income to $6,000/month.

If you're looking for a house hack I would wait patiently for the right 2-4 unit that works well for you and your own individual needs or I would buy an older SFH with an accessory dwelling unit (or the opportunity to add your own or convert an unused structure on the property).

The accessory dwelling unit shall be limited to a maximum of 1 bedroom.7.

However, I am not sure that if this space is converted, it would be considered an Accessory Dwelling Units (ADU), which the city prohibits.