Adding a tow-behind tank to a tow-between unit.

[Kevin Steeves]

Hey everyone, 
I'm looking at buying a tow-between air drill that is currently set up for single shoot, and anhydrous tank pulled behind. We don't have an anhydrous dealer close by, so that is out of the question. My thoughts were to convert the drill to dual-shoot and buy a second tank for behind the drill and that would be for my fertilizer, and the front tanks can be for my seed and starter fertilizer. 
Any opinions on if this is a feasible option or a smart idea. I price out new hoses and manifolds and stuff and it will cost about $3,500 for all that conversion as well as $4,400 for new seed boots and all. And then whatever another single shoot tank would be. So I'm just wondering if anyone has any experience doing it or knows if it's effective or not. 
Thanks for your time,
Kevin