My husband is the same way about steep drop offs and while we weren't towing, we drove our truck up there on 36 and it was a nice pretty easy drive both up and down.
You can avoid going through Boulder on 36 if you cut up to Longmont (not sure where you're coming from, but assuming from the South) and take Highway 66 across that way. You can get on 66 from I-25. As mentioned, there's some lights, but nothing hard and I'd do that way all day versus going through Boulder. I hate driving in Boulder even in a car haha!