I use my ipad as a second monitor occasionally, using air display. It works well to throw a browser up on and test. Or, even if you don't use air display, as

I use my ipad as a second monitor occasionally, using air display. It works well to throw a browser up on and test. Or, even if you don't use air display, as long as you're okay with the mobile browser for the testing, you can set up a local network, and just navigate to the test address. It's not ideal, but it's nice. I find the size of my multiple monitor setup is less a concern than being able to mentally divide tasks/contexts. ymmv