Audio amplifier mono operation and power consumption
Do not connect outputs to ground!

I would connect INR to ground through a resistor and a cap, per their "typical applications schematic".  If I were feeling particularly paranoid (which I usually am when going off-datasheet) I would connect an 8\$\Omega\$ resistor between OUTR+ and OUTR-.  Then I'd cross my fingers and hope the resistor doesn't see much of a turn-on transient (I'd probably back that up with some tests, watching OUTR+ and OUTR- on an oscilloscope while powering up my board).