Volume issues - advice needed

[FedoraDave]

I'm going to be brewing a batch with a very high-volume grain bill tomorrow (2/22). I'm got 14.5 pounds of grain, plus about 8 oz. of rice hulls. In calculating my water, I see I'm going to need about 4.5 gallons of strike water. The problem is, I've got a 5-gallon mash tun. That much grain in that much water is not going to fit. What are my options? The only thing I can think is to do the bulk of the mash in the mash tun, and the rest (maybe four pounds of grain) as BIAB at the same time, and then combine them.

Any ideas?

[mashani]

The BIAB way is how I would do it to save time, but if you don't care if your brew day is extended by some hours, you could always do 2 mashes and combine them in the pot for the boil. Just keep the first mash 150+ in your pot while the second mash is going so bugs don't start munching it.

[FedoraDave]

Yeah, I'd prefer not to add another hour+ to my brew day, so I'll go with the BIAB idea. I'll do ten pounds in the MLT and 4.5 pounds BIAB simultaneously.

I rarely make beers with this large a grain bill, so I'm reluctant to step up to a 10-gallon tun, since the 5-gallon has been working well. I may only do something like this about two or three times a year, anyway.

I'm also using about 8 oz. of rice hulls, since I've got two pounds of rye malt and two pounds of flaked rye.