deinterlace on the fly with an external recorder
The Blackmagic Design Tenarex 2D will convert a signal from interlaced to progressive on the fly: https://www.blackmagicdesign.com/products/teranex/processing

It doesn't record, but there are very inexpensive recording devices that will take a progressive signal and give you a digital asset from that (such as the HyperDeck Shuttle: https://www.blackmagicdesign.com/products/hyperdeckshuttle)