Leader size doesn't necessarily correlate to rod weight. For the type of fishing that you seem to be doing, you can go a bit on the heavy side.
To construct a leader, use the 60-20-20 rule, where 60% of the leader's length is the butt section, the next 20% is of an intermediate weight, and the last 20% is the tippet. For the type of fishing that you've described, using 30, 20, and 10 pound test should suffice for the sections of 60, 20 and 20%.
This is a general guideline and should be used as such, but you certainly don't need trout tippets down in the 7x range.