For your 8 square inches on one side (16 sq.in. for both sides) and you ignore the surface area of the edges (OK if the work is thin) 0.5 Amps will get you close enough to 4.5 A/sq.ft.
The wire dissolving at the electrolyte level means that your electrical connection to the work is very bad, only the wire itself is making electrical contact with the electrolyte.
Since the titanium wire is much harder than the aluminum work, it won't cold flow under pressure, with enough force, the aluminum work will. The connection here MUST be so solid it is literally liquid tight. If its not, the connection will fail.
This will be much easier to do if you use aluminum wire, the softer the better. A cheap source ($12 / lb.) for this wire is
www.parawire.com, a pound of aluminum wire will last a long time. You can use any size between 18 AWG and 8 AWG, 14 AWG will probably be the easiest size to use.