This code 

I hope I understood your need and this is the solution you want.

class SaleOrder(models.Model):
    _inherit = 'sale.order'
    _description = 'mark opportunity as won from sale order wen you confirm order'


    def _action_confirm(self):
        opportunity_obj = self.env['crm.lead'].browse(self.opportunity_id.id)
        if opportunity_obj.exists():
            opportunity_obj.action_set_won_rainbowman()

        return super(SaleOrder, self)._action_confirm()

Thanks

Hello Moe,

In sale order model we have a Many2one field named "opportunity_id" to "crm.lead" model. By using this field you can access all data of crm record related to that sale order. 

I Hope this will help you. 

Thanks & Regards,
Email: odoo@aktivsoftware.com
Skype: kalpeshmaheshwari