Plz have a look at the sketched communication flow in my second footnote (updated).

A CGI using JSON and DBI to run just 2 or 3 prepared statements returning AoAs should have less overhead than configuring a full REST/ODATA layer.

Without knowing your app I can't judge how complicated it's supposed to become later, hence justifying the long term investment into abstraction.

update

NB: if you put these SQL-statements into a separate module you can use and test them directly. The additional CGI/JSON layer would be transparent.