Here is a small pack featuring the textures I've reworked so far (JSGME ready for everyone to test).
It contains the following textures:
+ a slightly improved version of the bedsheets.
The remaining textures included in silentmichal's interior mod seemed okay to me, so I decided not to edit them.
Please, notice that I didn't test my reworked textures in game, but I kept on my HD their psd files, with unmerged layers. So, let me know on any change/improvement that might be still required
P.S @ silentmichal:
I think you should adjust the tiling fatcor of toilet's floor (metal tiles are too big compared to the ones used on the rest of the sub), and I also agree with vlad29 in thinking that Doenitz pictures hung on top of the toilets look a bit irreverent