I slept under "tarps" - ok, 2 ponchos snapped together- or under the open sky way too many times fighting mosquitos to even want to use a tarp anymore. Granted, the tarp gives you more room, ventilation in the summer and great views. But no-see-ums and mosquitos are not my idea of ideal sleep mates.
Find a lightweight tent, divide the load if you have to and go from there.