Wow, you have many projects :) Yeah 1 block wide is interesting too. After few hours I managed to create thin SV (2 blocks wide + shutter windows block s around it - they have 200 hp and are thinner than wall blocks) so its thinner than 3 blocks wide SV. Sadly I had to extend it to 7 blocks long in order to provide oxygen. Tested it on planet with 190 degrees temperature with fire storms, 1.6 gravity on indestructuble POI with 1 BA block entrance, 40 creatures, 10 sentrys, 20 spawners and it worked fine :) Sadly because of gravity I had to add 2 thrusters for sides and bottom.

Your link reminds me of my one cube project, back when I decided to make a full surivial HV/SV that would fit on one BA cube. I managed to do it, but their performance left much to be desired.

If you want something thinner check out version 1. I built it to be 1 block wide, but it looks goofy if you put a gatling gun on it.

From my experience I can say that 3x3x3 is doing very well while passing through the doors but it has problems with elevators. I was thinking also about creating 2 blocks wide but longer project similiar to yours. I will test such project today :) Creating such project with oxygen is extremely hard :/ There are planets with radiation and ultra high temperature so project without oxygen is very problematic there.

I'm trying to create similiar SV with and without oxygen. Yours looks nice but creatures can bite you from sides. The best project found in the workshop for this purpose is this one: http://steamcommunity.com/sharedfiles/filedetails/?id=949460146 I hope that it will give you some inspiration on building safe project :)