I use the same body, and shoot lots of long exposure night time stuff as well. If your doing hour long exposures, you're already fiddling with mounting gear, so small external intervelometer is the least of that needed gear. I have a custom VR rig that mounts multiple camera bodies that all shoot timelapse in sync. Imagine the cabling involved there and you can see why a single body with an external controller sounds like heaven to me.

You don't have to do high ISO anything. If you're willing to shoot 1 hour exposure (which are you really doing that on DSLR?), seems like you'd be willing to shoot 30 2-minute exposures, or 60 1-minutes. What doesn't motion blur out in 1-minute shots other than maybe cars at a red light? Also, how many 1 hour exposure shots can you get out of a single battery charge (2 batts if using grip). I know doing 45s exposures with short intervals will chew up batteries for me.

It seems to me that Canon has decided that if you're going to do longer than 30s exposure, you're going to be using bulb mode and an external controller. I know MagicLantern allows setting custom bulb exposures, but I haven't messed with that option. Its built in intervelometer isn't reliable for short intervals (anything 5s or less is iffy regarding consistent shooting frequency). With my wired controller, I can do 1s gaps. Anything less, and I start getting issues with dumping to card reliably on the old body. Using my custom arduino controller for .5s gaps with 1s exposure with camera mounted to car for motion blurry goodness freaked the mkII out for some reason. newer bodies handle it much better.