Stoov1,
This is a very similar problem to the one I encountered. It is the modulating controls that are difficult to have in a small system. Maybe I was too general in my initial outline.
Also, the ability for the client to operate the system easily is important in this case, although I realise...
I have been frustrated by the seeming lack of HVAC controllers which are easy to program and straight forward to use.
I am chasing something with a 7 day timer, which can operate a relatively simple setup of a couple of split AC units.
I am in the design field, and have had a number of clients...