We can't use prototype inheritance with product.template model

[Zodk2]

Odoo raises TypeError on Many2many fields that set manually the  relation, column1, and column2 like taxes_id, supplier_taxes_id, or route_ids and there are many references to product.template in model fields and methods. Even if you fix that error, the product_tmpl_id field still references the product template model and this will prevent Odoo from creating any record.