Well nothing on your team is massively weak to rocks by the looks of things so you may be better off just going for a bone breaking hyper offence rather than allocate a defensive spot for a spinner.The Lando-T idea sounds pretty effective actually, I'm gonna give it a shot. Don't want to have a teambuilding conversation in a cores thread though so that's enough though lol
Real quick though before you mentioned Landorus I was considering Donphan since he can spin stuff away without me having to more or less dedicate a teamslot for it. I'm probably leaning towards Landorus in this case to pose a more offensive threat but just figured it was worth mentioning.
Give offence a try, maybe with a physically defensive Rotom-W and see how it does for you. If it doesn't seem to be working for you and you feel crippled by hazard, maybe try a defogger since you're not focussing on hazards so much yourself. Mandibuzz seems to me to be the strongest physical wall in OU right now. Has great typing, insane bulk and access to Defog.
It's all about options and experimentation for you now though - you have a good core, try rotating different types of pokes throughout different roles and see what clicks. Something WILL click. Just like trying pieces of a jigsaw... If it doesn't fit, it doesn't matter how hard you try and jam it in, it will not fit. Good luck on it though :)