You can ask the driver. I know that on our return trip from US/IoA to BW, we had a couple that were 'supposed' to return to SoG. But they asked the driver (nicely) if there was any way they could be dropped at DTD. Since the driver had to stop at SSR as well, he said sure, no problem. But, I wouldn't count on it.
The monorail ride from the Polynesian over to the GF is only about 10 mins...so if you can't go to the GF with Mears, just hop on the monorail.
As for timing....I would think an hour would work but I would perhaps put it at 90 mins..then you can return to the Polynesian, freshen up and take the monorail over to your GF ADR.