Welcome to the RTA Forum!

The one factor you need to keep in mind more than any other is that in mid-February, luck is probably more important than route when it comes to winter weather. Every single route between Maryland and Oregon is going to involve mountains, and the chance of snow and ice (which of course will be a factor long before you get to the mountains). Going south doesn't significantly improve your odds of seeing good weather, and many times it can see worse weather than more northerly routes.

I-40 certainly isn't generically better than I-80, as it sees plenty of mountains both across the rockies, and then up the coast to Oregon as well. In your case, it would be among my last choice of routes, because not only is the weather not significantly better, but it also adds 500 miles, which is another full day on the road. That's one more day where you could see bad weather, and one less day available if you need to wait for a storm to pass.

The other reality is that if visiting Ouray is a goal, then avoiding mountains really becomes a pointless goal, as Ouray, with an elevation of 8,000 feet, is about as in the middle of the mountains as you can get!

But saying all that, I'd say don't worry about it. You've got more than enough truck to pull anything you could put in any UHaul trailer even through the heart of the Rockies, and with 10+ days, you've got more than enough time to sit and wait if weather conditions make it too dangerous/stressful to continue. Chains are fine as a precaution, but if you're pulling a trailer, I'd recommend just getting off the road if conditions are anywhere near bad enough to need them.

If you want to get to Ouray, I'd take I-70 across to Western Kansas/Colorado, and cut down to US-160 at Walsenburg Colorado and take that across to Durango, where you'd go north on the Million Dollar Highway to Ouray.

From Ouray, I'd head up to Salt Lake via I-70 and US-6, and I'd probably continue north on I-84 into Idaho, and cut across Oregon on US-20. Although, I have only limited experience with roads in this area and someone may have a better suggestions.