1.140cm or 158cm is still hard to hide. You can consider the locking ottomans and they seem pretty promising. With the internal lock, it looks like it doesn’t conceal anything.
2. Recommend you buy WM 140 + 156# classic doll: https://www.rosemarydoll.com/product/140cm-4ft7-d-cup-tpe-sex-doll-derrick/
After 3-4 years, you could buy WM 157B or 166C +: https://www.rosemarydoll.com/product/157cm-5ft2-b-cup-tpe-sex-doll-aryana/ or https://www.rosemarydoll.com/product/166cm-5ft5-c-cup-tpe-sex-doll-kelsey/
3. 130 – 150cm is the sweet spot for a new doll owner. The weight is very manageable, especially if you’re not used to handling dolls. And the height is realistic enough that she doesn’t feel like a toy. After your first doll, you will know whether or not you want to go taller and heavier for the next doll.
