Using POS Chip Card Reader

What are the best iPad choices for running POS chip card readers?

I just purchased PayPal's Chip & Swipe Card Reader, only to discover that it's not compatible with my older iPad 2. The card reader wasn't pairing. Although PayPal advertises it to be compatible with iPad 2, it is not. I discovered that the card reader requires Bluetooth v 4.0+. My iPad only has BT v 2.1. With another trade show coming up, I have to resolve the issue asap. I considered switching to the Square POS card reader but I'm hearing that I'll likely run into the same problem. Sadly, I'm facing the reality that my trusty iPad 2 is obsolete for my uses and seems the only way to resolve the problem is to upgrade to a newer iPad. What I want vs what I can afford are two different things. If cost were no object I'd go straight for the newer iPad with the 12.9" screen and loaded. Realistically, what would be my best choices in an older iPad, but not so old that it's likely to become obsolete soon?

Any help is greatly appreciated.