The answer is yes you can, its done all the time. But, you will not end up with less waste and get the same life out of the RO membranes. This has been tried over and over by the large manufacturers and better vendors and it only works for a time before the membranes fail due to insufficient flushing action. You must waste about 4:1 or they will fail sooner than later guaranteed.
My system uses a 150 GPD RO membrane and a 90 GPD RO membrane for a total of 240 GPD when water temp and pressure are right. In the summer months I can actually push more like 270 GPD out of it at 99.23% rejection rate. I kep the waste ratio at the recommended 4:1 and expect to get 5 to 7 years or more out of the membranes. If I reduced the waste ratio it has been proven in my area of the country I would get less than 18 months out of the membranes.
The only long term proven system that has sucessfully reduced the waste to 1:1 or even a little less than that and has probably in excess of 2000 hours on the membranes is a Spectrapure Ultra High Efficiency unit. It is a very unique system and you pay for the research that has gone into it but it really works.
Rolands situation is very unique in that he has almost pristine water to begin with, and I HATE him for that
. In most places it would never work for very long.