Hey, OP, you don't have to be too specific, but could you give us a general area/section of SoCal you are located?
The problem in our (LA) area is not distance (the height of Mt. Wilson and Mt. Harvard provide for STRONG reception and excellent coverage in areas without obstruction/terrain even at pretty fair distances--and your 30+ miles distance from the station towers that have the best/most desired content is not the problem), but the fact that there are countless communities built INTO the hills and deep into canyons and these hills and that hills just a few miles apart and those mountains and that mountain and often with the hills and mountains looming right over our heads.
The question for your situation is how far away are you from the obstruction (I take that to mean the hillside, etc.) If you are sufficiently far away, than two things can help: HEIGHT, and some power, but mostly HEIGHT. I just don't know your situation, and if even particular placement can help.
I can tell you I know of some house holds here that have no hope of ever getting any signal from OTA because, like my dear aunt and uncle, they live right next to that steep hill side or mountain--a whole lot of people do, and no amount of high power OTA antenna is of any help. And there are countless shadows cast by countless terrain here in places I would never expect it.
My situation is that I am not all that close to the First Effect obstacle terrain, but it is a ROYAL PAIN to deal with. my OTA must be placed at sufficient height, and most assiduously pointed in just the right direction to take advantage of the LOWER parts of the contour of the hills a few miles away that is the SWEET SPOT for almost everything at Mt. Wilson and just down the road (both in location and elevation) Mt. Harvard, and I still get some channels with low signal reception, but they can be stable the vast majority of the time. You would think things are flat in my area with no visible terrain, but, in fact, it is a gentle slope right into the unseen, but looming hills. I can tell you going just a few blocks north of my location, the even further slope makes getting OTA near to completely impossible. We are surrounded by terrain in the entire metro area. aside from a few places that will suffer from liquefaction in the coming big quakes. Those places a flat, but they are gonna sink
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Let us know how this all pans out. And go ahead and try some of the antenna gain suggestions others have offered and see for yourself it works. Otherwise, sadly the Slingbox product will soon be shut down by Echostar/Dish. Perhaps Dish Anywhere from someone else's home might work to watch OTA at your home.