The truth is, just about anything will kill a deer. A 7 mag is one of them for sure. I've killed deer with a .22 up to a 45-70. It ain't that hard. And I've killed them with a 7 mag and they were just as dead as my old 30-30 did it. Around here, a lot of times your deer tag will be in the same area and same time as elk season. That's a bit different deal. A 7 mag is a great elk hunting cartridge, so if a deer pops up, you got it covered as well.
As far as a deer being too close for the 7 mag, you have a couple options to avoid meat damage. If it's real close and I have some time, I will either opt to shoot it behind the ear, or else I will pull out whatever handgun I have with me just for fun. But really even if it's just 50 yards away and you have a good hard elk bullet loaded, if you shoot them through the lungs, the bullet hardly even expands and you get a nice little hole on the other side with not any meat damage.
I say, if you shoot it well, then by all means take the 7 mag deer hunting. Or a 243. Or a 30-30. Or a 45-70. Or a 25-20. Or a ..... whatever.