This is not leading down a path of success and successful implementation. At minimum you should have logins that segregate schemas. This way you can maintain objects for each company. What happens if a customer wants a stored procedure to operate differently than the one everyone else is using? Then your dynamic solution will not work and you will have to create a new procedure anyway.

The best solution is to have different databases for each company, or as stated before a default schema set for each company login. This allows for seperation of objects and increased security, and allows for greater manageability.