This adjustable laundry bag keeps all your dirty clothes in one place and the best thing is, you can keep adding to it until you either get to a laundry or run out of clothes !  You start with a small bag and just keep adjusting the horizontal strap to allow it to roll out.  when it is full size it folds in half  and has a handle, so you can still carry it. 
 
Your choice of mesh or canvas.  Both have their benefits to suit your situation....
If you keep your used clothes say in the back of your ute or if your clothes get wet or maybe you just need to hose them off first depending on the level of soiling, mesh might do fine as the odour will not offend anyone and mould will be reduced as you have airflow. 
 
However, if you are indoors - maybe a caravan, vehicle or tent, the canvas option may suit better to isolate the odour of laundry in need of a wash.