You should think seriously about using tarps a lot, either by themselves or in conjunction with a LIGHT one person, or at most a two person rig. I only sleep in the tent - all other activities occur outside.

The only critters that are likely to give you any problems are insects. When they are an issue, tents often may make more sense. You really only need a tent in bad (rain or snow) weather, when swarming insects are a nuisance, or perhaps when you are in a busy public campground which is not typically the case when backpacking.