You can create a position for officer in you operating agreement (even in an LLC) like a president. Even in an LLC where the member (or manager for a manager managed LLC) is the one officially with all powers, by creating this position and appointing someone for it, it raises much less level of suspicion by a third party.
You need to have in your operating agreement a good description on what limitation of power the officers have, but that's a neat trick.
It is way nicer to have John Doe, as President of ACME LLC signing than John Doe, as Authorized agent of ACME LLC. In the later case, the third party will often ask for a letter of authority where the member/manager will have to sign certifying that John Doe is indeed an authorized agent for this transaction.
Look at this