Best location : 1 in the porch wall and another at A.

Used a single unit or 2 units an switch on same time.

A) Single unit for bigger horsepower can be easily shot up more large airflow surface and more expansive stuff for what you paid for it.
Gas/water Pipes was go for single only.
Maintenance wise single discharge pipe for empty out take shorter time, even self-DIY clean out for short while only.
Yerly maintenance more cheap than used 2 blower at same time.

B) 2 units of indoor blower maybe look more nicer, but comes to maintenace wise, take more longer time to empty dust else for 2 units.
When a single unit water pipes dripping should empty for 2 units a same time.
Power consumption would be used more than 1 unit of bigger HP at lower input watt just 1830w only, for 2x1.5hp input watt was 1030x2 = 2060W.
The advantage to save up from switch on either one unit only.
And also ME model from 2.5hp and below does not built-in left and right auto swing and wide n long airflow.

C) Try to quote with aircon installer for single 2.5hp more expansive or take 2 units 1.5hp x are cheaper.

The hose and cable can run on top of the ceiling, just need to plan. Without plaster ceiling actually better.

What? you buy your house but cannot hack the wall? What is the logic on this?