What time in October are you going? DH and I went for our honeymoon the first week of October in 2007, and we did US/IOA on Friday and Saturday and it was EMPTY. We did almost everything we wanted to do in the first day, went to Halloween Horror Nights that night at US, and only spent a few hours there the next day (after spending almost all day at a timeshare presentation!), and accomplished almost everything. The only things we skipped at IOA was Dr. Doom's Fear Fall, the 2 water rides in Toon Lagoon, and the 8th Voyage of Sinbad show. At US we skipped Jimmy Neutron, Fear Factor Live, Terminator 2, and the Animal Show. Everything else we were able to ride multiple times!
Here's some pictures we took to give you an idea of crowds:
On Friday we were up super early to make the trip from our Disney hotel to our USO hotel, so we checked in and headed right to IOA when it opened. As you can see, we practically had the place to ourselves! We went over to US a little after lunch, then took a break in the late afternoon, got dinner in City Walk and went to
HHN. The next morning we went for the timeshare presentation and got back to the resort around 2 in the afternoon. We went to US and walked on to pretty much everything until we called it quits and went back to the room early to be rested for the plane ride the next day. So about 1 & 1/2 days, and we did everything we wanted many times over! I definitely think you can fit
MNSSHP into the mix! Hope that helps.