If you hire an inspector, don't use their person to scope the sewer, find a local reputable plumber, they may know the history of the area and or the building.

I am currently looking at a manufactured home in a very nice Mobile Home development. 

then you really don't have a problem...except that you are forced to switch horses in mid-stream which I know is not desirable....A new GC will not always charge so much more to take over a job mid-stream, it just depends on a lot of things (like the original GCs reputation).I would get a release (of sorts) stating that the original GC will warranty the work that he has completed and that the new GC is not liable for any work not performed by his company.

Coming from a warehouse/manufacturing background, I can tell you that there is how it should be, and how it is.

I challenge you to find and post a single reputable reference that does not show San Diego to have historically produced outstanding returns for a modest length hold.  

Reputable contractors will likely have some sort of social media presence where you can parse through some of their previous projects and work. 

If this is the route you are looking to take then let me know as I can help direct you to the reputable providers. 

On the flip side, agents may steer clear of companies with bad communication, payment issues, subpar services, unappealing commission rates, or bad reputations.

Here's a PARTIAL list:Office rentComputers, printers & softwareInternet & phone billOffice furnitureOffice supplies: paper, postage, ink, etc.Office liability insuranceAuto expenses: monthly payment, insurance, gas, maintenance, registration/plate feesBroker license fees: annual, monthly board & MLS fees, continuing education fees, E&O insuranceEquipment: lockboxes, signs, etc.Business income tax preparation and paymentsStaff payroll & payroll taxes Time Tasks: answering phones, calling past due tenants, scheduling tours, taking marketing pics, processing those pics, writing ads, researching rent amounts, posting ads, explaining to owners how rent determined & showing where ad posted, opening & processing mail, posting payments, bank deposits, scanning documents & posting to owner & tenant portals, explaining accounting to owners so they understand their monthly statements, taking pics/videos of repairs, finding reputable handymen and contractors, confirming they're properly licensed & insured and tracking annually, verifying repairs done properly, processing invoices for utility bills, repairs, taxes, city inspections, scheduling periodic property evaluations/inspections with tenants that don't want strangers in their homes, explaining to owners why taking so long, and more & more & more...

I have a stable long term job in manufacturing grossing approx 250k a year.