For your size family you can get a comfortable trailer in the wheelhouse of that Suburban. Look at some of the lightweight rear king slide models, with a bunkhouse in the front since you're planning on more kids. There are some compromises with those lighter trailers but they're still comfortable units and they'd be a good place to start.
If you really want a trailer the size of the one you contemplated originally, I'd advise you to trade the Suburban in on your favorite brand heavy duty truck look at fifth wheel models with comparable floor plans. I'm not saying there aren't some really nice travel trailers available, but fifth wheels are a lot nicer to tow down the road and you save on total vehicle length by having some of the trailer up over the bed.
But option A is going to be a lot cheaper, and since you've never had a trailer before it might be smart to take a smaller first step into this stuff.