Some players do this really well: Joel Quarington, Nadia Gale, and (the late) Red Calender. It requires that you use PIVOTS a lot in your left-hand technique, which is generally thought of as a mature technique. For young hands, a bass tuned in fifths might pose quite a strain to the left hand, unless a innovative approach to left hand technique is applied: something like introducing the pivot before any shifting (a pivot is a rocking of the hand's "weight" or form on both sides of the thumb - without stretching the fingers. A shift is where the thumb moves. An extension is where the fingers stretch to "reach" a note beyond the palm width, the thumb does not move). So, I would let a player make that decision sometime after a "solid" technique is established... but you might be able to convince me that you have a way of approaching the bass which, albeit new, works for a particular student. 5ths opens up the range of the bass and allows certain pieces to actually be played more easily. Many of us use a 5th on the bottom all the time (Edgar Meyer tunes his bass a, e, b, e all the time and transposes. I use g, d, a, d for all orchestral playing and most solo). Then there are various solo tunings.
The tuning issue for bassists has been around for centuries. Bottesini was known to have tuned his bass up as high as a fifth above normal tuning. SO: use the standards fourths for now. But being open to alternate tunings is a GOOD thing ... I believe.
Patrick
