Consider riding the Cumbres and Toltec Narrow Gauge Train while you are there.

I just went over that pass last fall and it should be a piece of cake. I would think that your V-10 would be very comfortable running about 3500 RPM on the pulls - My Old '88 460 would turn 3000 for miles pulling our TT and never raise the temp gauge.

The Cumbres/LaManga road is excellent and if you pay attention on the down hill runs and keep it geared down you should have no problems. There are some sharp curves on the north side , but they are well marked with highway signs.

I grew up here and have been over every major pass in Colorado either pulling a trailer or in a big truck in the last 65 years and without a doubt, Red Mountain north bound is the worst descent - Steep and Many sharp curves. Loveland Pass is also bad, but there is normally no reason to go that way.

Whatever you do, DO NOT ride your brakes. I led a lady driver whose husband cannot drive now due to vision problems from Durango over Molas Pass and Red Mountain last fall and she had no problem once she learned the importance of gearing down and letting the motor do the braking. She had a LARGE 3 slide 5th wheel and had the truck brakes smoking when we got to Silverton. After I explained the proper technique, there was very little heat when we got to Ouray. She had no problem on Cumbres/LaManga.

Traffic may back up behind you, but don't let that rattle you. Just maintain your comfort zone and pull over to let them go on by if you get a chance.

 

Thanks Colorado Native:

I have been fishing the Conejos Canyon and the streams on LaManga and Cumbres for the past 45 years. Have driven the passes many times in the pickup alone, but have never towed over them.
We always come in from the south through Tres Piedras and Antonito. However, someday I see me towing over the Chama and Pagosa Springs and just was wondering if I have enough to get up the LaManga side. The downside into Chama isn't as bad.
You seem to have the answers I was looking for. Thanks again.