steam as sous vide

You would have to see what the temperature variance in the steam oven is. Most sous vide equipment is .1C - .5C though you could probably get away with a 1-3C variance as long as you stay away from the lower cooking limits and times.

I currently use my Cleaveland Convotherm combi
Oven everyday for sous vide both in
And out of the bag (low temp vapor) for
Roasts, fish, poaching, chicken etc.
Lots of people say it can't be done, but you have
To look at the avg temp throughout the entire cooking
Process. If you have a 3 deg +/- temp variation
During a 24 hour process it won't affect the final result
As much as what you would think. I even do my beef filets
The same way only I season with pepper only, seal chill vac, then cook @ 50 C till my internal reads 50C, then
Chill. During service, I rewarm in the water bath, remove, blot dry, reseason with Salt and pepper, seal in evoo, napè with butter, a slice of garlic and a thyme sprig to order. I get a perfect filet every time with only an 8 min pick up! Give it a try in your Gag, I bet it will come out great! Just be SAFE!!!!!