My biggest problem with the goal zero "boulder panels" is that they're not the most efficient design.The boulder 200 panel is not particularly efficient at 2160 in^2 for 200 watts of power.
I don't think you're thinking about this properly, especially since your idea to avoid the less efficient panels is to wire the output from the slightly more efficient panels through a less efficient path for charging. That makes no sense! The Boulder panels are more efficient than you give them credit for!
The Boulder 200 panels are more efficient per sq. in. then the manufacturer's size specs might indicate because these are panels that have been inserted into a "suitcase frame". There is a frame with corner protectors for impact resistance and suitcase handle hardware that sticks out past the actual solar cell itself. The manufacturer includes this hardware in the dimensions. Also, because of the suitcase design, it's actually two 100W panels so it's unfair to compare it to a 200W panel that cannot be folded. While you can find more efficient panels advertised, the devil is in the details. I've found the Boulder panels to be very conservatively rated. I mean, I've actually got more than 215 watts out of the 2 100-watt panels on multiple occasions. And that's up here almost to latitude 49 degrees N.
One other point, even including the ruggedized hardware, the Boulder 200 is not 2160 sq. in., it's 2140 sq. in. (according to the manufacturer's specs and my own measurement). Measuring just the aluminum frame of the panels (and not counting the hinges, ruggedized corners and handle hardware) the dimensions of the frame is even smaller, 26" x 39.5" (x2). These are the dimensions that should be used when comparing to other panels without the suitcase feature (because the corners, handle and hinges can be removed). So each 100W panel is 1027 in^2 (2054 in^2 for two 100W panels). While you can find panels more efficient, I'm not sure it's a big deal if they are a couple of inches smaller, especially not if their ratings are not as conservative. The Boulder panels do have a rather large margin around the active area of the cells before the edge of the glass panel and I suspect this margin, combined with your unequal size comparison, is what contributes to most of the difference you noted.
And, yes, the Boulder panels are more expensive per watt than residential roof panels. That's because they are 100-watt panels that have been ruggedized and have had hinges, a handle and a kickstand added for portable use. They also come pre-wired together and with a 6' lead with Anderson connector (and a protective zippered dust case). Smaller panels like these will cost more per watt and for portable usage, I would not go larger than 100-watt panels.
It does seem you are trying to solve a problem that's not even a problem. I hope this helps.