If you are willing to jump borders to Northern Virginia, Potomac Yard still has a lot of potential, but their prices are incredibly high to start out with.

I wouldnt buy it unless its right at the border with an area that is a c neighborhood or higher.  

This one in particular had been on the market for a year in a very remote area (East Texas border near Louisiana)... 

I live in North Texas (up by the Oklahoma border) on a lovely ten acre spread.Currently, I'm an Executive Image Consultant, Author, Speaker, and Mom.

Maybe even across the border in Vancouver up to Longview?  

I don't mind giving you my input if you want to provide the address publicly or privately - I've done multifamily in-fill, single family in-fill, and lot split projects (one of the current ones is about 10' from the La Mesa border, so I know that general market).The hard part is figuring out how much any proposed project is going to cost, and how to control your risk in a market where labor and fees are high and the fundamentals don't necessarily support the sales prices.  

Flipping a house, even if Dennis does 2-3 a year, still takes months to complete plus if he has a home office in which he runs the flips from and researches for new property all while taking the tax deduction for it, is all running a business and i would be very careful playing that gameAgreed, this is a highly subjective fact intensive determination and border line cases are notoriously difficult to predict, with selected outcomes at times being contrary to what one would expect.

Seems like you'd face similar problem investing in Newport Beach itself right now, though I imagine your rentals are in other areas - likely close to your 45 minute border. ;-)

Interesting discussion............your market is an international border away from mine, most people in your area speak French and yet the challenges are pretty much the same-how to get away from those fours, fives and sixes on the cap table!

Some might not let you own within 50 KM of the coast or border....like Mexico.