I have been trying to hang indoors for 10 months now, with different hammocks, and failed. My first try was a Ticket to the Moon kingsized hammock. I love the hammock fabric, but I could never get a flat lay no matter what I tried. I then tried to use my Warbonnet Blackbird, which had served me great outdoors. The lay was flat with the BB, but I couldn't get rid of the calf ridge (which I never had outdoors). The same was true for the Warbonnet Traveler, which provided a lovely flat lay, but also a very uncomfortable calf ridge. I have no idea why, because the ridge vanishes outdoors - my guess is, that it has to do with the suspension length, because that was the only thing I could not change. The ridge was a bit better when I added hammock springs to the suspension, but not enough to sleep comfortably.
I also tried a Brazilian hammock, but although I picked the longest one I could find, the lay was nowhere as flat as with the Warbonnet hammocks. Not flat enough for me to sleep in it. I also had problems with my underquilts. The lay got more curved when using an underquilt, although I bought a huge one specifically for use with the Brazilian.
My last try was to order a Wilderness Logics Night Owl, and I received it a couple of days ago. I'm very happy to say that all my problems seem to be solved now. The Night Owl seems to be a very forgiving hammock: I hung it without a ridgeline, and with different suspension angles - it was comfortable no matter the angle. Probably the level of comfort differs, but compared to all the miserable hangs before, it doesn't matter. The lay feels a bit different to the Warbonnet, but not better or worse. However, the calf ridge is gone almost completely (there is a slight bit of pressure depending on how I lie in the hammock, but not comparable to the Warbonnets), and I also like the high walls, which prevent my feet and head from going over the edge accidentally (happend a couple of times in the Traveler). I think that the Night Owl will be my everyday home hammock from now on. I wish WL would offer a cotton or linnen Owl model, which would be nicer to touch and would not create static electricity. But it would not matter to me with regards to warmth: I couldn't sleep without an underquilt, even in the Brazilian hammock, no matter the temperatures.
I would highly recommend the WL Owl for anybody fighting with calf ridges and needing a flat lay.