This isn't a hermit wall, but the wall is definitely achievable by a hermit. Brick will be the dominant wall and iron will be the wall you protect your bell with. I DO like the idea of it only taking 1 steel 2 wrought and 30-50 iron (as it would be a work gate rather than time gate) but the materials here definitely don't seem that bad. (this wall is really only limited by the number of cementation devices you have. If you have enough you could theoretically have a whole 100x100 up in 2 weeks)
and honestly if iron can go in to stockbins I don't care how much this wall costs it's worth it