Do it the easy way.
What do you do when you're in the woods and you trash your derailleur? you make a single speed.
Shorten your chain a link or two, have the chain around the small cog up front then put the chain around a gear in the back so that you'll have a lot of slack. Then pedal and shift the front derailleur into the middle ring and it will take up all the slack. You will have to experiment a bit in the back gears to find the one that works best.