I had the same turn around time....

I just pulled off my yellow tags on my bag and got off at other Doha stop on the bus, I then just paid for my visa and picked up my hire car and explored doha.

If your a silver or gold cardholder then you can have a shower in the lounge at Doha but your bags will be checked all the way through... The lounge provides - towels, razor, shampoo, toothbrushes etc etc