In terms of a right hand bat right now and not at the deadline, i did a quick search.
In triple A, over .200 iso, 26 or over (post prospects), over 10% walk rate and under 25% k rate, and right handed or switch.
The list is Jose Barrero, Davis Wendzel, Brennen Davis, Brewer Hicklen, Buddy Kennedy, Stuart Fairchild.
Of that list only Wendzel, Davis and Hicklen have options. Davis is corner outfield only i'd say, but has the longest history of hitting for power. Wendzel is first/third, and Hicklen is outfield only.
I'd see if Seattle would take a small prospect for Davis and see if he can take Sosa's spot.