After seeing the extra-deep open 3700's used for plastics here I gate it a shot. Works great!

But I need to haul five of them around as a refill kit when I head out for longer trips. Replacement line, backups, etc. 

I suppose I could just toss them into about any old big bag, but it's nice to be organized. 

 

Favorite bag that can hold this much? It'd be workable if it could do four deep and one regular, but five deep 700 is preferred.

 

Well, while not cheap, the Bass Mafia bag would hold them. A TON of storage.

So quick math according to the plano dimensions

 

3700 / 3750 - 1.94 inches deep

3700 deep - 3.25 inches deep
 

8 x 1.94 = 15.52

5 x 3.25 =16.25

 

Something like the Cabela's Advanced Anglers™ Tackle Bags without Utility Boxes in the Magnum size are on sale (but Out of Stock online) would probably fit your needs but basically you are looking for any bag that will hold 8-9+ regular or non deep 3700s

 

6 3700 bait coffins, 1 3700 DD bait coffin and tons of storage for line, pliers, sprays, dyes, glasses, scales, etc.