I've used Tucano leg covers (sometimes called skirts) on 3 of my previous scooters (Yamaha Majesty 250 & Honda SH125/300) and found them very good, especially in Winter as they keep your knees & legs from getting cold. I didn't bother to use the bib most of the time, just folded it under the main part onto my lap (even in light rain).
However I found in prolonged rain with the bib up & hooked round my neck, water would trickle down from my jacket inside the bib into my lap so I usually wore a long waterproof sailing jacket that covered halfway down my thighs to combat this; a pair of light waterproof over-trousers would do the same job.
When parked up, the cover can be fitted over the entire seat to keep it dry.
I haven't bought one for the Swing since it probably won't fit due to the leg wind deflectors & anyway, the weather protection on the Swing is such that so far I haven't got wet the few times I've been caught out in inclement weather - as long as I keep moving that is...!