I am not sure what to do here - resolving the V7 chord results in the next I chord being incomplete, so I can’t write the 5-6-5 neighbour motion since there’s no fifth. I can’t write an incomplete V7 chord either since the question already provided the fifth in the melody. Any help would be appreciated! :)
The solution here would be to "frustrate" the leading tone in the tenor and move it down to the fifth of the tonic chord.
When it's in an outer voice (the soprano or the bass), the leading tone of a V chord will resolve up to scale-degree 1. But when this leading tone is in the alto or tenor, it can be "sprung" down to scale-degree 5. Doing this will result in a complete tonic triad.