RPI is only one of the variables, though it has the most weight. I do think that the Cajuns will likely need to finish top three in conference. Finishing fourth would mean that the Cajuns would need to leapfrog a higher place finisher in the selction process. Could the Cajuns leapfrog FAU? Possibly if they are close in RPI as the season sweep would grab the selection comittee's attention. Could they leapfrog WKU? Possibly if there were a vast RPI differential as currently exists (23 spots) ... despite WKU winning 2/3. I do not have to say that it is important to beat these two teams should the Cajuns meet them in the conference tournament.
Regardless of where the Cajuns finish (3rd, 4th, or 5th), we had better hope that if the Cajuns do not win the SBC Tournament, that FIU or Troy does. I know that the selection committee says that they do not take into account conference when determining bids ... I just do not believe it. I think it plays a role, even if it is in the back of their minds. They know exactly how many teams have been slotted from the various conferences.
There are several variables that can mitigate the required RPI for a postseason slot. Obviously a conference championship is one. General conference finish is another. Head-to-head record vs. your competition for those final spots is important. Records vs. Top Base RPI XX is very important, as is non-conference RPI, ... etc. You get the picture. This is why I think beating Rice is important. It can help mitigate a lower RPI.
Finally, you must take into account the # of "stolen bids" resulting from the conference tournaments. Each "stolen bid" results in one less available at-large spot for teams on the bubble. Normally, there are about three stolen bids. I have seen as many as five since the new postseason format commenced. But I want to say that for the first time ever, there were no stolen bids last season. I would need to go verify. But you get the picture as to how variable it can be and how an RPI number is simply a broad measure of what it will take because the value of the other variables changes from year-to-year.
That said, assuming "normal" numbers everywhere else, a Top 50 RPI ranking gives the Cajuns a shot ... with each ordinal ranking position very precious. But at this point (considering the Cajun resume), nothing in the Top 40 RPI is a lock for an at-large ... whereas in some years, it would have been.
Brian