Are there any laws that would prevent me from even considering taking this suggestion before the Board of my association?

In order to determine whether you can enlarge patio, some practical questions need to be addressed.  Will expanding the patio take away from any common area or otherwise adversely impact the neighboring lots or units near you?  Is the common area a strip of land which is otherwise inaccessible by anyone else, so that by expanding the patio you are actually taking some of a landscaping and maintenance responsibility off the association's hands?

Civil Code Section 1363.07 governs your request.  Unless the area in question is inaccessible and not of general use to the membership, then it may take a vote of 67% of all the members to approve what you want.  This statute limits the ability of a Board to grant exclusive use rights.

Will the members approve this?  Perhaps the association would adopt a project-wide change, so all members can do what you propose.

NOTE TO BOARDS: Any time you permit a member to do something on common area, consider a license agreement to document that the permission is not necessarily permanent.  This written agreement can spell out the member's responsibilities, protecting the association and future members.