That's pretty adventurous trip to Alaska with your Burb and a 35' travel trailer in tow. I used to own a Yukon XL Denali that I pulled with my current Keystone Bullet 308bhs, the fraternal twin to your Passport. So this is my take on your choice of TV.
If you ever looked under your Suburban's underbody, take a look at the suspension components, including drive axles, shocks/struts, and spring mounts. Now head on over to your nearest GMC dealer and look at the underpinnings of a 3/4 or 1 ton truck. My Yukon XL's components looked fragile to say the least. Absolutely no comparison in performance and handling.
The reason I point this out is that I had the same opinion about my trailer when I first hitched up to my Yukon. These long trailers do not bode well with a 1/2 ton build quality. I had to upgrade a $3000 Hensley hitch to eliminate sway and trailer movement. In doing so, I ran over payload with a substantially heavier hitch.
I didn't want to but ultimately I knew I had to. At the beginning of last year camping season, I upgraded to a new Ram 2500 Megacab. With an enormously larger wheelbase and suspension to boot, My 35' tow behind does not misbehave, even with the mid grade Blue Ox Sway Pro I originally had.
The drive is so much more relaxed and enjoying. Now, my wife drives about half our mile during any given trip without trepidation or irritation. (at least never irritated with piloting our rig; with me, that's another story). I just wanted to give you some insight these very long pull-behinds.
Remember too, even with just you and the DW, your payload is limited to around 1400-1500 lbs. At 15% TW on a 7600 GVWR trailer, your dropping close to 1140 lbs on the hitch ball. Add another 100 lbs for your WDH and I bet your remaining payload will be less than 250 lbs. For me, that's not much margin for travel across an entire continent with 7000 lbs in tow.
