Having your storage pig trailer equipped with a motor and blower package is a great idea to give you the convenience of loading and unloading the trailer at your job site, so yes, it is highly recommended you install a motor and blower package.
Diesel gives you the added flexibility of loading and unloading anywhere but it does come at an increased cost. 74 HP diesel is a standard diesel engine for cement storage pigs.
Electric gives you reliability and consistency of power, but requires an electrician to hook up the unit on your job site and requires you to have 208-230/460 volt electric service. 50 HP is the most common electric motor installed on storage pigs, but 60 HP is available if you need.