In my area here, an accessory dwelling is restricted to about 800 square feet.2) 8-10 weeks to build an entire second structure from the ground up?

From what I understand, that would not restrict you.

I found a property in 21207 in Dorchester on Liberty Height Ave and I am interested in buying it.

If you were in a SFR that would be one thing, but as @Jim K. states - you do not have a right to record others without their permission and I gather that is the source of the pushback here.I fail to see how a Ring doorbell would restrict the peaceful enjoyment of the unit or violate the right to privacy of the other tenant.

I’m thinking about the north park, city heights, southeast, la Mesa area.

My observations:- Limited available land in desirable areas- High cost of construction for any type of structure- Developers are only making money on rehabs and luxury units, so are ignoring starter homes- Many people do not want small/starter homes- Very restrictive zoning in many communitiesSome communities (San Fran, Seattle, etc) have a crisis, and they won't solve the crisis until they ease up on zoning and also work on public transportation in a meaningful way. 

@Dametrius Clark My house hack was in Cleveland Heights and it worked out fantastically, some of my friends also house hack in Cleveland Hts but I would totally do Lakewood too, it just didnt work distance wise to my job.

If I can find the code restrictions again I'll post the link.

Are the setbacks restrictive? 

Because I love dogs I did allow a dog, but I did enforce a breed and weight restriction.