Anto,
Tarps are a really lightweight, packable and flexible alternative to tents. They just need something to elevate at least one end, and a bicycle can serve admirably there. JimK and I discussed this in an earlier thread and it offers possibilities. Tarps can be made very large and roomy if you like to spread out and you can adjust headroom by changing the pitch.
Our own John Saxby has a great deal of experience using a bivy sack, a tent, a tarp, and various combinations together and has posted photos and detailed descriptions of them to the Forum.
There's also this fellow...
http://www.christownsendoutdoors.com/2014/11/tarps-shelters-my-award-winning-feature.htmlI don't think any mention of tarp-camping would be complete without mentioning Ray Jardine. He's literally written the book on the topic:
http://www.rayjardine.com/ray-way/Tarp-Book-Essential/index.htm ...and offers compete kits for a reasonable price so you (or June, who has the skills already in hand) can make your own. He's got a complete line of kits and materials available, and offers the plans in his publications so you can make them from fabric and such you get on your own.
Ray has refined his tarps so you can close them down against high winds (
http://www.rayjardine.com/ray-way/Tarp-Kit/BatWing/index.htm ) or stay secure from Bug Invasions (
http://www.rayjardine.com/ray-way/Tarp-Kit/Net-Tent/index.htm ).
This is a great way to get some top-quality kit with just the features you want...for far less money and the investment of a little labor. Much lighter and more compact than many commercial offerings, as well.
I've no connection to Ray except to say I've always found his writing and philosophies to be thought-provoking. He's big on ventilation, and makes some very good points, particularly about choosing a camp to avoid -- or maximize -- katabatic airflow (
http://en.wikipedia.org/wiki/Katabatic_wind ). It could well explain why you got so very cold that one night. I've sometimes found just a few meters' difference in pitching location can make a big difference in how warm I sleep. A good book to curl up with on a cold winter's evening before the fire is _Trail Life_:
http://www.rayjardine.com/ray-way/Trail-Life/index.htmAs for sleeping hammocks, those generally require trees and insulation under you inside the hammock to stay warm through the night in cooler climates. A few can be pitched as mini-tents on the ground if no trees are available...but are generally smaller inside than you've preferred in a tent.
Anto...have you considered a tarp-tent? There's even a company of that name:
http://www.tarptent.com/ The idea is to use a pre-shaped tarp and then equip it optionally with an interior floor or net chamber or pitchable with or without an inner compartment so you have the versatility of each kind of lodging as you desire. Here's an example that ticks most of the boxes you've mentioned wishing for in a tent:
http://www.tarptent.com/cloudburst3.html 3.25lb/52oz/1.48kg for a 3-person tent isn't a bad weight and it pitches very quickly in 2 minutes and can be closed up snug against drafts.
Best,
Dan.