1. A lot of people warn about weight because very few people understand what 32kg/70 pounds of complete dead weight is like to handle. Either positioning for sex, carrying, storing, manipulating to dress, etc.
If you have ever had to carry an unconscious person, then you have an understanding of what dead weight is like to deal with. Many people that do not pay attention to the weight have turned around to sell the doll in the sales section due to the weight. or when they talk about other dolls say they wished their doll was lighter than it was.
2. If your plan is to leave your doll lying in bed undressed and do nothing at all with her (aside from missionary sex while using a condom), sure – get a 30+ kg doll.
My doll is 33 kg, and I wound up buying a new extra-tall bed so that she’d be at crotch height while lying in it.
3. Positioning the doll is not the problem, lifting her is. If you are not strong it will put a lot of stress on your lower back even with proper technique. If you are dead set on her then I suggest some core exercises and using a weight lifting belt when lifting, it will keep your spine stable and reduce the chance of injury.
4. For first-timers, dolls over 30kg are not easy to handle, especially lifting up as someone suggested earlier. I think 20-28kg is a good weight to handle. You might have to go for a smaller size for that lighter weight. Alternatively, some of the manufacturers manage to produce dolls with lighter weight.