Partial Mash Witbier Recipe - Any Thoughts?

[hurleyci]

Mostly hoping to get advice on the mash schedule and the quantity of wheat used. The recipe I'm using is as follows:

30 Litres,    OG: 1.051    FG: 1.031     ABV: 5.0%    IBU:10.9     SRM: 4.3

2.5kg Flaked Wheat
1.5kg Mariss Otter
1.8kg Extra Light DME
0.2kg Flaked Oats

10g Brewers Gold (AA unknown!) @60min
20g Tettnang (3.7%) @ 60min
Zest of 3 Oranges @5 min
25g Coriander Seeds (crushed) @5 min
20g Tettnang (3.7%) @ 0min

WLP400 Belgian Wit Ale Yeast

So, I've never done a protein rest or a mash out, so from reading up, how does this sound as a mash schedule? I'm using 4.2kg of grains, so was going to mash in 12 litres of water.

Dough in @ 40c for 20 minutes
Protein Rest @ 50c for 20 minutes
Saccharification Rest @ 65c for 1 hour
Mash out @ 75c for 10 minutes

I'm doing brew in a bag, so was then going to drain the grains as much as possible before transferring to 18 litres (1.5 times mash volume) @ 70c for 20 minutes in order to sparge the grains.

I've never used wheat before, so unsure of how to handle it. I have read that I should be using rice hulls with that much wheat. My LHBS stocks oat husks, but are unfortunately sold out at the moment. Are these an adequate substitute for rice hulls? And are they absolutely necessary?

Also, I've been told to aim for around 50% of my grain bill as wheat. At the moment, my grain bill is around 60% wheat, but that's not including the 1.8kg of DME. Will this leave me with too low a final proportion? I don't know what to do if that is the case as I can't really increase the amount of wheat used, or else I'll have very little diastatic power in my mash!

Any advice would be hugely appreciated!

[Jacob]

With BIAB you don't need to use any hulls. You'll simply take the bag out, when hulls are added to help with wort filtration.
Also, you'll be absolutely fine with 60% of wheat in you grain bill.
I've even brewed beer using only wheat (well, smoked wheat), but that's a different story

[hurleyci]

Great, thanks! Excited to get started on this with the weather improving!