Here's a source for silk, think I pulled it off of here and haven't ordered yet. http://www.dharmatrading.com/fabric/silk/silk-habotai-fabrics.html
I'd throw M90T into your against-skin options, I love the fabric against the skin. Though I haven't used it in 70f temps. You may need only that and a shell with the lightest insulation. M90T doesn't breathe as well as pertex quantum but feels fabulous (T=taffeta coating). Though my liner/shell weighted 9oz with M90T and Quantum (and baffles and drawstring) on my quilt before sewing. So you'd be close to 8 without any insulation. Its breathable but wind resistant, with a dwr though, so that may help depending on shelter type.
If you'd wear longsleeve/long underwear baselayers anyway the feeling against the skin is somewhat moot. (that's an if, I might but I don't think everyone would)
60-70 is the temp your house is mostlikely, what do you use on your bed? I think a silk/pertex "quilt" would be really nice at the right temp range.
I ordered from Quest some wicking material, the remnant piece I got was ~4oz/sq yd (sewed wicking buffs out of a small remnant to try it). That might be an option, it's just like raw baselayer material. A shell would be optional if you have a closed shelter.