If you go to Bribie Island and head up the inside of the island past Whitepatch you will come to the rangers offices. the road breaks right from there and takes you on a sandy inland track up to several sites along the passage to as far as Poverty Creek/ Stockyard Point. Not challenging but it is offroad and the location isnt bad either.
The pine forests in the western side of the passage are not bad either although not 4wd neccessary unless you opt for mud tracks. There are a few creeks with good access points and the fishing is quite good also if you attack it right.
Personally I would be looking at Jimna Forestry. Can be challenging, steep, slippery, winding and very scenic away from the main tracks. Some very nice creeks and waterholes can be found thru that area as well as some outstanding wildlife.
Someone will no doubt correct me on this if I am wrong but I seem to recollect that about 3 yrs ago State Forestries abolished the permit system for the pine forests and I am pretty sure native forests like Jimna. There are some locked no entry forests around still I am sure.
The roads from Lacey's Creek up thru Brisbane Forest Park towards both Wivenhoe and Somerset are awesome driving and some areas are quite dangerous with very tall and almost vertical drops beside the tracks. It is or was a locked access area but have ventured into there several times over the past 30 yrs offroading.
Jack.