How can I prevent a few apps from off loading?

Hi,

I really appreciate and value the feature that off loads apps I don't use often. Certain apps are big and I only need them on a summer holiday (NightSky for example).

But there are a few apps I occassionally need and I want them never to off load. They are also small in size.

When I need them there is an unforseen incident and they are going to help me out big time with providing my with information in seconds. I can't be bothered to download them again. It has happened during such an urgency that I was connected to some wifi-network which required me to login. Before I figured that out and also made some extra space by downloading big apps I ran out of time (missed a connection/appointment).

I would like only certain apps to never off load.

Perhaps I should automate some weekly script to open and close those apps? Would that prevent them from off loading?