I don't grow in a terrarium for just the reasons you mention, and find no need for terrarium culture for any Drosera if the humidity is average 40% or higher. You should be aware that even a thin layer of saran wrap will cut the useable light spectrum considerably, and light is primary concern for Drosera. I would indeed worry about the temperature range you state. The Drosera from Brazil can take some surface heat provided the roots are kept cooler, but this is difficult to arrange in a closed terrarium. I grow my plants on a rack, as close to 6 tubes as possible with nothing in between. Air circulation is also desirable and missing in terraria. If you decide to try a more open approach, be sure you acclimate your plants to the lower humidity by going slowly as they will be "soft", and will easily burn. After some exposure to the more open scenario, the growth will be stronger and the leaves will be able to take it. All my Brazillian Drosera were grown from seed, and never required this process, so you will need to be attentive to signs of stress, and if this happens you must make adjustments. I find these plansts to be more prone to fungus attack than most other Drosera and suggest that the cleaner the medium, the better. If you get moss or algae scum on the pots surface I would be concerned about this. Pure water is a must, the habitats where these plants grow is very pristine. I think one of the most critical factors is the night time drop of 5-10 degrees - in my neck of the woods this is generally available except in the hottest months, but I can't say the same will hold true for you, so keep this in mind. Best of luck with your plants!
I regret the article I published is not available online, but I have covered the basics of it I think. I would also suggest caution if you use the "double pot aqueous culture" method outlined here if you can't provide the redwood sump. I haven't done any comparison studies, but feel there is a good likelyhood that the antibacterial properties of the mulch play an important role in root and overall plant health. Red cedar would be my second choice for a sump.
In any regard, please let us know of your success/failure with the method you are using.