so, the weather stayed in the 50’s and quite comfortable. I put the emergency blanket between the tent and rain fly, as well as one between the tarp and tent. I definitely felt that the top one helped retain the heat, I have no idea if the bottom one added, but it didn’t detract. Plus now I have an extra one for my car. I had camping booties (https://www.rei.com/c/camp-booties) and a balaclava (https://www.rei.com/search?q=balaclavas) plus my 32 degree rated sleeping bag AND and 4 rated sleeping pad on my cot. I also heated soapstone and had them in my tent but I think they only really help if you wrap them and put them in your bag (ala the hot water bottle trick). Overall, I think the sleeping pad and the booties made all the difference (compared to similar weather without using those). Plus, if the weather unexpectedly dips, I will have these on hand to still get a good night’s sleep!
I’m going to assume since you have a cot, that you are car camping.
We use this Mr. Heater Portable Buddy Heater on every trip. We’ve been comfortable in our 15 degree down sleeping bags in our roof top tent at temperatures in the upper 20s. It’s also nice to have the propane heater at night when there are fire bans. We keep it on a cookie sheet so it won’t tip over on the memory foam topper. Although, I’m going to ditch the cookie sheet for a taller set up, because the heater melted the foot box of my sleeping bag.
It has an oxygen sensor that will turn off the heater if it senses low oxygen (nothing ruins a trip like carbon monoxide poisoning). You can use the heater on 1 reg Coleman propane tank, on low, over night. We bring a 20 gal propane tank with a long hose/adapter and run it through a space in the bottom on the tent. Most of the time, with temps over 40*F, we just turn it on before we get in the tent to warm it up. Even on low it can heat the RTT to over 75 degrees, so we shut it off to sleep. Our 15 degree sleeping bags can handle the temperature drops from there.
Seriously, this is one of the best pieces of gear we ever bought.
Unfortunately in colder conditions you must eliminate airflow and create a “thermal barrier” to trap or maintain heat. An insulated sleeping pad is a necessity but the cot allows for airflow beneath you…defeats the purpose. Had your pad been directly on the ground, you would’ve been warmer. Next up is your bag…even if you are a hot sleeper, a 32 deg bag would be marginal in 30 weather. On a cot, even with an insulated pad, a 20 deg bag might not do the trick (unless you brought some of the mentioned sources of heat). Mesh on your tent body is another heat stealer. In cold weather months, I use a 4 season tent TNF VE-24…which eliminates airflow and can assist in lowering inside temps by 5–10 degrees, depending on fellow occupants, which can make all the difference to shivering sleepless or a sound nights rest.
I have been on the fence about getting this heater myself. My friend who lives in the midwest uses it and like you swears by it. I might just add it to my gear in the case I find myself again in what was supposed to be warm weather but decided to drop to without consulting me!!! Thanks!