Connecting 10 IP Cameras To An Analog Only Old Pelco DVR?

Customer has an Pelco DX8100 DVR which is no longer supported (I bet that's news to everyone). Anyway, I need to add 10 name manufacturer cameras to cover some new entrances. Would like to install IP domes and connect, via analog, to open DVR channels, then later migrate these cameras, with existing analog cameras, to IP. I know that Panasonic cameras have an NTSC monitor output, but per their manuals, these outputs should not be used for anything other than set up and trouble shooting. Possible use a D-A converter but i seem to have difficulty locating such a product that does not cost more than the customer is willing to pay (not to mention that the converter will be scrapped when the customer goes IP).

Suggestions? Anyone know of an IP camera with an analog out? Inexpensive decoder?

I can't think of any GENERAL reason the analog service ports couldn't be used for a regular DVR. There may be some specific to those cameras, such as an inability to turn off OSD menus... or like I discovered with an old CW484 dome, that disabled the SDIII function entirely when something was plugged into the service port, which made it pretty difficult to actually adjust the SDIII settings *facepalm*

Aside from that... I've used the analog output on several IQEye IQ-A11 domes to drive a public awareness monitor. Done the same thing with a couple of Dahua 3MP box cams. The camera is outputting analog video to the service port whether something is connected to it or not, so I don't see why feeding it to a DVR would be a problem.