I dont think the disco is worth renting.
What we did was perfect for what the wedding was. Dinner was on the beach and we paid extra to have dancing on the beach. I brought a iPod with a playlist for dinner and for dancing. They set up a dance floor, lighting, sound and a DJ. We played the music for dinner and after everyone was done, the bride and groom got up, walked to the dance floor, signaled the DJ and did their first dance in the sand.
We could only have that set up until 11. After 11, whoever still wanted to party, went to the disco.