That would be quite an adventure. If done during the summer when temps are warm you can take full advantage of the LEAF, but that's still a lot of climbing at highway speeds which will impact range. I agree with dgpcolorado to get a portable L2 EVSE (such as EVSEupgrade.com) with a selection of plugs for RV parks at least as a backup plan - and check in advance that the parks are functioning and have space. I'd also plan to keep the speed to 65 and lower - though for much of the route the limit is 75 - to extend range.
Plugshare shows a location with 2 J1772 Level 2 connectors in Idaho Springs, which would be a good place for a top-up, then nothing until Vail where there is a large number of them. That's about 65 miles which is possible but iffy at highway speed with lots of hills even with a new LEAF. If in doubt you could detour to Breckenridge where the town hall apparently has one. From Vail it's another 60+ miles to Glenwood Springs where 2 L2s apparently reside in a parking garage - and if in doubt you could stop at the CostCo in Eagle which has one plug. But after Glenwood Springs you'll need a plan B, such as an RV park, as it's almost 90 miles to Gd Jct where allegedly a Spring Hills hotel and a Solar company have some ports.
Of course, you can't rely on these locations listed on PlugShare being in operation and available, which is why you need the backup plan. You'd probably need at least 3, possibly 4 charging periods from start. It would be a fun trip if you planned some outdoors kind of stuff while waiting for the charges.
Unfortunately, all of those well-placed Tesla superchargers on this route can't be access by the LEAF.
Red Leaf: 2012 SL, lease, acquired 21 November 2012
Blue Leaf: 2011 SL, purchase (new, was dealer demo), acquired 4 March 2013