I'm flying a P3P, and yes it is possible to set a new home point (in situations as you describe). Not sure if it is the same for the P4, but after the recent updates the Homepoint toggle was moved to the top of the first page of the MC Settings menu. Hope this helps.
Have fun & good flying!

You have two options to reset the home point.
1.  You can reset the home point to the current location of the Phantom
2.  You can reset home to the current location of the R/C controller (mostly for situations where you are moving .. shooting from a car or boat etc.

So if you intend flying in an area where RTH would create a problem, you can send the Phantom to somewhere clear, in the open ... reset home to there (no need to land, you can do it hovering any height above the chosen spot)

The homepoint reset feature used to be on the front page of the app but in the current version it's hidden in MC settings.

Hello wrathofkhan, you can set a new home point during the flight:

Setting jome point to RC location requires that the device running the GO app have a GPS.

Hey!  I havent used my P3P in a while, so maybe a stupid question. I updated all firmware today and went out flying. I can see that on your Go app under Main Controller Settings, you can reset home point to controller or drone. On my new dji go app I dont find it anywhere. Did they remove this is latest version?

lotrlks Posted at 2016-9-18 22:43
Hey!  I havent used my P3P in a while, so maybe a stupid question. I updated all firmware today and  ...

They moved it from the working screen and put it in the MC settings of the ap.

labroides@yahoo Posted at 2016-9-19 00:58
They moved it from the working screen and put it in the MC settings of the ap.

Well there is no such thing under my MC settings. I checked 100 times. It seems to be on top when you enter Mc settings for all you guys, but for me first settings under MC setting is: Multi Flight Modes

lotrlks Posted at 2016-9-19 15:57
Well there is no such thing under my MC settings. I checked 100 times. It seems to be on top when  ...

Try connecting to controller and powering up aircraft. You should be able to see all then. Many of the settings are passed to the aircraft, so dependant on it being turned on.

lotrlks Posted at 2016-9-19 22:57
Well there is no such thing under my MC settings. I checked 100 times. It seems to be on top when  ...

As the above posts states, you need to have the aircraft powered on.

DJI-Ken Posted at 2016-9-19 18:28
As the above posts states, you need to have the aircraft powered on.

I was out flying a few days ago, and it was the same. Will try again later today

lotrlks Posted at 2016-9-20 13:40
I was out flying a few days ago, and it was the same. Will try again later today

Go through the MC Settings and it's there.