Outnabout David (SA) replied:

Darren,

Should be available from a caravan accessory supplier. In Adelaide we have a company called Dario Caravans who make caravans and sell accessories for the van market. I remember seeing a low profile inner spring mattress on his stand at the recent caravan and camping show here.

Arkay replied:

Also ads in Caravan World magazine

Member - Rohan K replied:

Also makers of Sofa beds. You can get a 4" queen-sized inner-spring mattress from one of them. We were thinking of going this way but tried the inner-spring mattress from our current sofa bed and found it way too firm when put on the solid bed base in the camper-trailer. If we could afford it, we'd go for a latex mattress.

macca replied:

Darren,
I notice a few distributors at the Caravan and Camping show in Melbourne yesterday had that type of mattress on display. I didn't take much notice of them as I wasn't looking for that sort of thing. The navigator also mentioned it when we were looking at some campers

rolande replied:

Darren,
Prestige Jaco in Geelong sell them for $350, give them a ring if interested
Rolande