Are chain ring spacers a good solution to adjust chain line? I recently converted my mountain bike from a 2x10 to a 1x10.  I have a Shimano XT Hollowtech ii crankset and I like it a lot, but its traditionally a 2 speed crankset.  When I'm in my 1st gear on the rear, there is some cross chaining going on and no matter how well I adjust my rear derailleur, if I back pedal a little bit, such as to get my pedals in a good position to get on the bike and take off, the chain will drop into the 2nd gear cog. To remedy this, I have found two potential solutions.


Buy a new 1x10 speed crankset such as the Shimano Zee. This obviously is a more expensive option.
Get some longer chain ring bolts and some chain ring spacers.


My question is will option #2 be sufficient for mountain biking?  I wasn't sure if adding spacers may somehow cause some sort of vulnerability in the crankset by possibly not allowing as much force or tension on the pedals? Or am I delusional and it does nothing to cause any additional weakness or vulnerability to the crankset?  If spacers are completely safe for my application, this would be the best option.
Yes spacers are fine for this. It sounds like you want to move a few millimeters - 2 or 3 millimeters is fine and the bolts can handle it. 

A word of caution about bottom bracket spindle: make sure that your crank is clearing the chain stay. Inspect this under load. You might look and think you have enough room for the shorter BB but on your first ride you can put a few nice gouges in your chain stay when you put the hammer down.