Hello world : )

Besides doing my morning sit when I have all the comforts of my own place, I am also sitting couple more times during the day whereever I am at the moment when I have time to sit. Imagine an office place, a green patch downtowi in a city, or a quite corner in a shopping mall.

I do need something under my bottom to be able to sit comfortable with my back straight, and also something on the ground below me so I do not damage my clothes. 

As a workaround, at the moment,I am carrying along a blanket to put beneath me, and I only sit on a slopped terrain, so my back is straight. I can't carry along a normal cushion

I am thinking an inflatable block shaped zafu could do the trick. I don't like the round ones. 

Does somebody offer some ready made kit for this? Or could you link me to something similar? Or share some pro-tips, and personal experience with workarounds for sittining "anytime, anywhere" ? : )