Hey, sounds like your after an interesting drive between the two locations....gloryhole crawl?
lol however, you will likely find that the majority of gloryholes are in male toilet blocks between the two destinations and then there are those at purpose built locations such as adult shops.
There are 'holes' in Cairns if you want to start further north, Mackay, Gympie, Fernvale, Brisbane and the Gold Coast with Cairns, Brisbane and the Gold Coast having some not in toilet blocks. Though the Gold Coast ones I think are male only these days as they have closed the Couple friendly ones.
Though keep in mind that most local councils close off any active spots pretty quickly but good luck.
Steve_s Glory holes in Brisbane are in Everything Adult, both the Valley and the City, in the Porn cinema sections - $10 entry allows you to come and go - pardon the pun. Ask the person at the counter and they will sign you in and take your tener.
As for Mackay, they used to be at the Toilets at the Marina Mulherin drive or whatever.