Is including government support information on a provisional application cover sheet sufficient?

No, including government support information on a provisional application cover sheet is not sufficient to meet the requirements of 35 U.S.C. 202(c)(6). The MPEP states:

Providing information concerning government support on a provisional application cover sheet does not satisfy the requirement of 35 U.S.C. 202(c)(6) which requires that the a statement be included within the specification of such application and any patent issuing thereon specifying that the invention was made with Government support and that the Government has certain rights in the invention.

The government license rights statement must be included within the specification itself, not just on the cover sheet.