DWR Bivy?

DWR bivy should have similar to less condensation than the WBP. Near freezing I imagine it would be very similar.

Yes you would want a full coverage tarp with the lighter bivy. The actual size will be highly dependant on the weather you expect and your comfort with cramped spaces – if you've used 5X5, I bet you'd be have with 5X8 or 6X9.

I'm curious, Pete, since I've considered a similar setup (5×5 MLD tarp + wpb bivy) — other than the issue of weight, have you been happy with this combination? Also, please let me know if you decide to sell the 5×5 tarp. Feel free to send me a PM if you want to keep this thread on topic — I was going to contact you by PM, but it looks like you aren't set up to receive messages.

It has been adequate for what I have used it for. That was mostly bicycle touring though. The only real drawback was that the bivy was kind of a hassle if it was hot and buggy. Retreating from mosquitoes to the bivy on a hot night was less than comfortable. Fortunately I have only had to deal with those conditions rarely.

If I expect a lot of biting insects I tend to take my tent. When I rode from San Diego to Sarasota I kind of wished I had sent the bivy and tarp home and had my tent mailed to me when I got to the Gulf Coast. Those Louisiana skeeters were brutal!

The tarp was pitched a variety of ways and also used to just pull over the top of the bivy and exposed gear when it unexpectedly rained. I don't think it would be much fun in a week of steady rain, but I have had a night of rain a few times and was OK. I will say that on a bike tour I did get a room sometimes when I expected really hard rain.

I actually have slept on top of the bivy and without the tarp quite a few times when the weather was nice. The open air and view of the stars is great. The bivy is very warm and comfy on a cold night though.