I fish a lake that has some deep areas that I think would be good for a c-rig.  I've never fished a c-rig so I've done my homework and read all of the wonderful advice on these forums.  But based on what I've read, it seems the recommended rod for a c-rig is a long rod (at least 7') with a MH action.  Problem is I don't have a rod that fits that description.  Is it worth trying the c-rig on a 6'6" M rod?  Or should I just wait until the wife will let me buy a new rod before I try fishing a c-rig?

You can fish a c-rig on any rod that has enough backbone to set the hook. I use a 7' Falcon Carolina Lizzard Dragger H and a 7' Falcon East Texas Grass Rake M/H, both are at least 10 years old.

My friend has used a 6'6" medium rod for Carolina Rigging for a long time.  He catches fish on it just fine.  As mentioned before, you need some backbone because you are moving quite a bit of line on your hooksets.  As long as your leader isn't really long, you shouldn't have many problems in using your rod until you get another.

If you looking to buy a rod and don't want to spend alot Allstar made or may still make one that can usually be found new atleast through Ebay stores for around $40. It's a nice rod and it works pretty well for me.

i've never tried a c-rig on a M rod, but that's not to say it won't work.  try it and see how it works for you.

one thing that might help would be to use braided line for your main line, use good sharp hooks, and maybe use slimmer baits to help in getting a good hookset.

Well, a 6'6" med. may not be ideal but you can bet your life it will work.  I would do 3 things a little differently if I was going to use that rod...

1. use a lighter weight  (3/8 - 1/2 oz.)

2. use a shorter leader (10" - 15")

3. be sure to wind all the slack out and use a horizontal sweeping hookset

These things will help you get a better good hookset, especially with with a shorter, lighter rod.  

Braid will also help (as mentioned) but I wouldn't change over to braid to help in this one situation.