Check out the above link to a page on the main site. It offers many variations on how to use a tarp to build a shelter from a very simple lean-to to more advanced folding, guy line, pole, and stake intensive shelter.

There are replacement stuff sacks that you can put your tent in before lashing to your pack that are water repellant and help to protect it from general abuse.

Years ago when I used to backpack, we would split up the load between the members of the party. Usually two people would use a tent but only one would carry the tent. The other person would carry something of similar weight like the axe, stove, more food, etc. A tent and sleeping bag are typically the two heaviest parts of a backpack rig. Backpacking tents are typically very small and low to the ground. Usually only enough space for two people to lie down next to each other and little more.

Many nights I setup the rain fly only and not the tent. In the event of rain, it would keep me dry unless a very strong horizontal wind at ground level. During cold weather, the tent provides very limited but some body heating trapping effect. It also provides additional wind and water resistance.