RSTV Vest? 86Y harness question?

I am really thinking about getting a RSTV vest instead of a radain.... especially for my 3-across. It would be nice to store too since it would be just for daycare use. Also, how does the 86 Y harness work? I hate that michael is in a booster, but he does sit nice in it, but every time he is in a harness he gets carsick(i tried him in my friends lil' girls regent the other day and he puked in the car-and he loves the regent).

So.... I need to purchase a Nautilus when Logan outgrows the Chase(I think he has awhile...he is 34 pounds and has about 3 inches left in it mabey(he just on top slots). My daycare boy has about 1 inch mabey left in the scenera(or less)... and is 34 pounds...

So, that ask, how long does it take buckle a kid in a vest?? And where can I buy one? I might have up to 6 kids in my car at once(still waiting for one daycare mom to tell me what days she is coming-hopefully I won't have that many at once)..and I rather not take Hours buckling them in. Michael can buckle in the regent, Logan will probally be in the RSTV Vest, baby at the time(10 months) in safeseat, baby at the time 3 months in snugride, Michael in Parkway, Just 6 year old girl in FPSV booster, Daycare boy(3 1/2) in chase.

Any pics of kids in vests? Are they pretty safe?