Silicone spray lube...lots of it...and S-h-o-v-e while it is still wet!

I'm a bit worried, though, about using sanitation hose on those drains. More worried still that there was clear PVC tubing there. Wow.

Usually drains like that use 4-ply marine exhaust hose, which is a real thrill to get on, too. With that stuff, you might want to try clear silicone GREASE on the fitting and a heatgun on the hose before you go a-pushin'. It's a bit awkward, but it goes.

Best,
Dave