Baking My Own Sweet Potato (Yam) Chips - Help Correct My Current Methodology
The dense nature and high sugar content of sweet potatoes can make them difficult to turn into crisp crunchy chips without burning, even when you ARE frying them.  This is the reason so often sweet potato fries are soft rather than crisp.

I have never tried baking them into chips but your method seems to be very sound.  Any higher temp is going to burn them even more quickly and a lower one is going to just turn them to mush by the time you cook them longer to try crisping them.

Here's a slightly adjusted method:  Try slicing them closer to 1/16th of an inch and then place them between two pieces of greased foil or parchment paper.  Preheat two baking sheets in the oven for about 15 minutes so that they're hot when the sheet of potatoes goes onto it.  Put the sandwiched sheet of potatoes on the first hot pan and place the second one on top to "press" them so that they're essentially "oven frying" between the sheets of paper/foil.  This still may not work as the steam will be trapped but pressing them between two preheated pans may help.

My primary suggestion:  Fry them and don't eat the whole batch.  OR Fry AND eat the whole batch and don't do it too often.  

Many times it's just best to do things the traditional way and enjoy it, than to try substituting and having a less than ideal result.