I always use about 10% C60 for APA and AIPA. If you want something with less impact on flavor, you could try 1/2 lb. of carapils. Mashing at a higher temp will increase body, but also have an impact on flavor.
Yeast can also have an impact. One of the reasons I like WY1450 so much is the silky mouthfeel it leaves in the beer.
So many ways to skin a cat!
10% crystal/caramel malt will add body, but it will also have a significant impact on flavor (even the lighter varieties). If you go this route, go light if you're shooting for the "west coast style" (carapils, C10, etc).
Other things you can try:
1. You can increase mash temp. Try the upper end (158F) next time and work your way down if the result is too full/sweet. A 100% Maris Otter grist is a great place to start in a deliciously simple hoppy beer.
2. Add a touch of flaked wheat or oats (3-5%). I like Golden Naked Oats (which are malted, available from NB) instead of the regular flaked stuff.
3. Increase the amount of Chloride in your water. This will also have an impact on hop expression and bitterness, but it will enhance the perception of body without increasing residual sweetness or reducing fermentability.
Make one small change per brew, omitting the change in the next brew if it doesn't get you closer to your target.