Talk it over with the wife, put it on layaway if possible to ease the sting for her. However, having a light rifle like a Forbes isn't going to improve your chance of success on a Colorado elk hunt, preparing yourself physically and more important mentally will do more than any rifle. A light rifle definitely make the hiking a little easier, but as long as your Ruger is no heavier than 8-8.5 lbs with a full mag and a sling you'llbe fine.
That elk tag is going to cost you a lot of money, plus travel expenses, and even more if you actually put one on the ground. I'd say set a realistic budget for your elk hunt and add 10-20% for unexpected expenses, then figure if a that Forbes rifle leaves you the budget for your elk hunt. The Forbes rifle will not make the hunt any more memorable, but it could eat up money that would be better spent on your trip.
It sounds like a nice rifle, I hope you can work it into your plans.