A local recorder is a pretty typical solution. Perhaps consider on-board / edge recording to eliminate a box. Wireless or 3G/4G seems to be more trouble / more cost than it's worth considering you already have a T1 in place.
Can you get a commercial cable modem at the location?
A T1 is pretty small for dealing with HD video, but I think it also depends on just how often you think they are going to need to get at the video remotely.
I think that no matter what, you're going to want a local recorder, it's really not feasible to try and record HD video remotely.
+1 for local recorder... also, if the entire system isn't decided on, look to something that allows easy integration of multiple sites in one VMS/client screen. I can't speak for others, but I know both Vigil and Dahua systems seamless combine viewing and management of multiple sites into one interface on their thick clients.
Matt - yes, we have enterprise level ware.
A T1 offers 1.5Mbit upload, so I would think it would be enough for remote viewing 2 cameras. Especially if you use the second stream, or if your recorder supports transcoding.
Sure, you could view them at a reduced resolution/framerate. But you're not going to be able to view any sort of a high-res stream over 1.5Mbps.
Definitely a recording unit onsite for this if you want to take advantage of those HD cameras... For interrogating and viewing the video remotely 1.5Mbps should be good as you can do it through transcoding or 2nd stream (if transcoding is supported or both HD and lower quality streams are recorded) pretty efficiently depending on your VMS. However, once you find what you want 1.5Mbs would be slow to pull back the full quality video... you also have to consider the others that are utilizing this T1 connection so just make sure to try to work with the lower quality streams as much as possible.