maybe you did answer it yourself when you named "non-diversity".
The antennas should be placed closed together at lamda/4 wavelengt distance, keep in mind to calculate with speed of light not sound. @800MHz it is about 4".
...the most common misusage I see is one antenna upper left corner and the B antenna lower right corner of a room. And people saying that gives the best coverage.
yep ...but it is non diversity, in a good diversity installation the reciever is heavily switching between two antenas. ...need more coverage? install more diversity pairs
Tilt one antenna some degrees maybe 30 degrees to cover polarisation losts. ...up to 6dB
And of course find out the damping of the antenna cable and maybe boost ...but avoid clipping
pimp the beltpack antenna to avoid it is direct connected to the sweat skin ...cost up to 20dB!
...just some ideas from far away 
