Australian Car Repair Issues? Ask an Auto Mechanic for Answers ASAP
If your aircleaner lid is now secure, you should be fine as long as a back fire doesn't reoccur.
The backfire occurs from a lean condition while on gas.
Can you use petrol at cold start and for the first 5-10km until the engine has warmed up?
Hopefully you will find a LPG workshop on your trip soon.
Hope this helps.
I hope my advice has been of assistance to you.