If you want to avoid unsealed roads don't go via Urandangie. After a good dry season you'd possibly get through with a standard car but after the recent rains, probably even 4WD is not the go yet.
Try
RACQ and then click on the Road Conditions link, and/or
NT Road Conditions , where you want the Tennant Ck and Alice regions.
The Urandangi-Tobermorey Rd followed by the Plenty Hwy (and the Sandover) consists of about 700-800 km of unsealed road, flood plains etc. Not recommended in your vehicle. Good in a Patrol though!
As of today 30/1:
Plenty Highway (and Sandover Hwy) From the end of the seal to the Queensland border High clearance 4WD Plenty Hwy is recommended for 4wd only.
If it was me travelling before April this year, I'd go via Broken Hill, Port Disgusting, sorry Augusta (stay at the Standpipe Golf Motor Inn, Highway 1 (Cnr Highway 87) Port Augusta SA 5700, ph: (08) 8642 4033) reasonable rate & rooms, great Indian restaurant.
The reason for this route? If there's another large rain depression, as recently brought widespread rain to NT, Western QLD, NSW; you may not be able to drive from Mt Isa westwards. The Stuart Highway from PT Augusta is less likely to be closed due wx.
If you go via Isa, recommend Barclay HWY to Three Ways, left to Alice (500km) or right to DRW 1000 km.
As others have said, carry plenty of water (20 lt bag should be good), and suggest SAR Time arrangements with friends, just incase you do break down.
Driving at night is frought with danger, I know of some girls that left Isa early one morning and hit a beastout of Isa and were severely injured. I hit my first roo last November when I left Alice for Darwin at 0200 'cause I couldn't sleep. $1700 damage wasn't worth it!
