What is the thinnest mash possible with BIAB?

[gbx]

I'm no sparge BIAB mashing a really small mild right now with 4.5lbs of basemalt (pauls mild and briess 6row), .5lbs baird's C75 and .75lbs of flaked oats in 26qts of water. Its gonna sit for at least 3 hours at 67C/153F. ...so really really thin mash.

I've done 7lbs in 26qts but nothing this small before and I'm starting to worry about the oats and the DP of the mild malt. Whats the thinnest you've ever gone?

note...just so you don't think i'm completely insane making non-alcoholic light beer, with the invert i will be adding the gravity will be a respectable 1.030

 

[Euphist]

I did a mild with just under 8 lbs in about 32 qts....came out just fine

 

[gbx]

Yeah...i think its fine too. My pre boil gravity was at my expected OG after I added the syrup! I expected 70% efficency but got 77%