Andrew,
The Crossbreed Supertuck is a great holster for large, heavy guns. Here's the magic of this kind of holster. The backing is leather. The holster itself is relatively thin kydex.
Go buy yourself a Supertuck for something like a Glock 17/M&P9 or similar. Then use a heat gun and reform the kydex for your Ruger. et Voila! A supertuck for your ruger.
I purchased a Supertuck to carry a Commander 1911. I soon realized that I was too much of a wuss to deal with the weight. It wasn't conscious, I just never reached for the 1911 and it just sat in the safe. So I used a heat gun to reform it using a Glock 19. I'm actually carrying it now.
There are some things to make sure of when doing this.
1) make sure you preserve the sight groove. I used a slim screwdriver to reform it.
2) make sure the gun sits deep enough into the holster so the trigger guard is covered
3) make sure to cut the leather away enough so that you can get a proper grip on the the first time. No re-gripping allowed.
Thats it.
PM me if you want more info on how I did this.
Don