I can help you out here. Periwinkle. (vinca) I took some by the roots, it grew wild down by a creek and transplanted it here and there in front of our retaining wall in the front of our property and on the hillside beside our house and in a year it spread quite nicely on it's own from about a dozen little plants. I didn't have access to town, I did what I could with what I had, back then I didn't have the internet or credit cards, that was a long time ago. I lived in the mountains in CA, it snowed in the winter and the vines would die back some and still double or more come spring and summer better than ever and hold the hill side back against the rains and snow melt. I believe we were zone 7 then. I hope this helps you. Deer did not like to eat the periwinkle either, they left it alone in the 13 years we lived there. Because of the mountains I didn't have a sprinkler system and threw some water on the roots I could reach from time to time but they really survived on whatever water they received on rainfall, some years good, some bad, but year after year the periwinkle always returned bigger and better than ever. Didn't matter on hills, they climb on their own or over rocks, I mentioned mountains? Our temps went to 17 below.

Daylilys and ornamental grasses would work and once established will keep the weeds out. You might have to mulch the first few years until they are well established. Deer don't bother either of them, at least not for me. Juniper bushes would also work, they come in a variety of heights and forms. Whatever you do don't plant english ivy!

I agree that daylillys don't care on soil conditions or watering but will die out in the winter and won't help hold soil in. I believe the ornamental grasses will also, I don't know zone 3, is this so? There's another ground cover called sandwort, arenaria, that grows pretty dense and there's a couple of varieties for zones 2-9 used as lawn substitues or in rock gardens. It is an evergreen from what I can tell it's mostly a shade plant. Don't know about deer, maybe someone else can help out there.
Cistus or rockrose is very pretty and grows well and deer don't bother it but I believe it starts in zone 4.

Also Aaron's Beard, Creeping St Johnswort, (Hypericum calycinum), deer resistant, creeping ground cover, it's an evergreen but can be a semi where winters are really cold. and meant for zones 2-24. Takes poor soil, some drought, fast growing, will control soil erosion. Hope these ideas will help out also.

Daylilies are hardy in zone 3. I used to live in Thunder bay, Ontario and grew them there. It's zone 3. The periwinkle myrtle is hardy here, in zone 5. It may also be hardy in zone 3.

My preference is for native plants. Periwinkle is very reliable (invasive, in fact) but is not native. Maybe some prairie grasses native to your area? Native grasses tend to be very deep-rooted and drought tolerant once established. I second the reccommendation against English Ivy. English Ivy is a bit of a menace and is not nearly as good for erosion control as it is touted to be. Perhaps the Canadian equivalents to the County Extension Office or forestry dept. or agricultural station can help with suggestions?