I've just arrived home from 4 months around Europe and West Africa and took a Bivi bag + Tarp combo. For me it was the perfect setup.
My main reason was weight, I wanted full camping and cooking facilities to keep costs down around Europe, but wanted a total amount of soft luggage I could comfortably take off the bike and carry. Plus I only had a small bike.
I used a tarp (with one elasticated side which I stretched along the bike) with a cheap spare tent pole propping the other end, a Goretex Bivi, and a small groundsheet with mosquito net I made. I left the pole in four sections (as in without the stretchy string), so I could use however many of them I wanted to shut the tarp down in bad weather, or allow me to use the tarp without the bike.
The bivi bag is far warmer than any tent (which lots of people don't seem to realise), the tarp provides a large shelter area (you'd need a heavy tent to get this much space) and as it's a modular system you can use as much or as little as you need.
The whole lot is just over 1 kg (with guys, pegs, net etc.) and packs very very small, but altogether the components cost me less than 80 GBP. To get a tent this light you have to spend over 300 GBP (double skin anyway). Plus I had all the stuff bar the stretchy tarp.
I've just found a picture of it all set up
HERE.
So basically lots of people here are recommending your tent, which is fine if you don't mind the space and weight - but if you want to go lightweight, I say take your bivi...
Eddie.