Quote - I must use defaults and not tweak anything because this model is for sale in the marketplace, so I must know how to model it well for good Poser render or I won't be able to sell it.

That can't be right, if the model is for Poser, then you have any settings required in the file you supply whether it's a CR2 or PP2.

If your item requires any settings that can only be set by the user, then you'll need to mentin that in the ReadMe and should consider supplying a sample scene (one corresponding to one of the promo renders would be a good idea).

Obviously if you're going for compatability with older versions and/or D|S, some settings may not be available, but this mostly affects what you can do with materials unless you supply several version/application specific setups.