We used them under our hybrid mattress for comfort. Worked very well, kept us from bottoming out.
No sure how effective they would be to eliminate condensation.
2013 Jayco JayFlight 26RKS
2013 Ford F150 Ecoboost FX4
2003 Coleman Bayside / 2011 Jayco Jayfeather X20E -- RIP
2012 Tacoma Sport DCSB / 2013 Tundra SR5 - RIP