As far as weight, I'd like to do more backpacking, so it is a concern. I would prefer to sleep in the open, but should probably get some bug protection.

The small 2 person domes seem light and with two poles are extremely easy to set up, so I'd like to go with one of those. But you can't really afford to get wet, and weather is tough to predict.

I don't really want a roommate so I prefer a smaller tent. 5x5 is fine if you sleep diagonally.

What about asphyxiation with throwing a tarp over a tent? are tarps airtight?

If I'm driving to the campsite or hiking less than 5 miles to it , probably wouldn't freeze to death if I got wet, just go back to car. but for an overnight trip, need to stay dry. Concerned about hypothermia.

Thanks for all the good replies so far!