I hike with my wife and friends, we're mostly weekend warriors and (so far) keep to the coast and foothills of northern CA. I always carry our tent which is an older model Eureka 2-person which weighs in around (sit down for this) 6-7 lbs fully packed. My scale is junk so I don't bother trying to work in ounces. I wouldn't call us "UL" by a long shot, but definitely weight conscious – and I want to lighten my pack.
I'm interested in a single wall shelter, such as the Lunar Duo. The room sounds great (I'm 6-2), and compared to what I'm lugging around now, the weight would be awesome. I haven't convinced my wife yet, and maybe she's got some valid concerns. We just got back from a few days out at Coe State Park where we got a little rain unexpectedly and I was using the fly for a pillow… she got a little wet and woke up cold (we have down bags). The concerns are:
– Is it a bad idea to mix down bags and single wall shelters? Changing bags is not an option for us.
– If we have to carry bivy's just in case, should we just look at getting a lightweight double wall tent like the MH Skyledge or MSR Hubba Hubba instead?
Thanks for any advice!

