Can you do it? Sure! That's what I moved to after dealing with an excessive amount of trub and debris from my inital start with BIAB. I gave BIAB 2 honest trys and both times I screwed up my volume into the kettle. Because of that, I picked up a 5gal cooler and used a 5gal paint strainer as a "sieve" for the grains, and drained out the factory spigot.
That did work - and came with some obvious issues that I'll explain:
1) Controlling the rate of the drain when taking your runnings, especially when trying to volurph (or however it's spelled, it's late and my brain's clunky) to set the grain bed was a PITA.
2) My EFF sucked, mostly becuase the heavier sugars in the work collected BELOW the level of the spigot, which also left a considerable amount of deadspace in the cooler.
Now, there were also some things that were positive:
1) I could accurate hit my boil volumes every time.
2) I could take accurate readings with my refractometer for the initial runnings and subsequent sparges to see where I was loosing sugars
3) It was easy as heck to clean with the bag in the cooler I could just lift out the grains and put them in the compost box
4) My wort was clearer without all the trub.
So, even though I went to the cooler, I still ended up springing for the valve and a simple CPVC manifold, which allowed me to address the two main issues I faced. My EFF shot up, and I could control my drain flow easily.
I still use a 5gal paint strainer bag in my cooler, because it makes dealing with the grain SO much easier, and I've yet to get a stuck sparge with it. Eventually I hope to move to a Wilser bag, but the HD cheapo's working fine.
I do hope to revisit BIAB with an induction setup, but for now the cooler works fine for me.