Nice, definitely post another pic once you’ve put all the guys in.
I’d probably just use the parts as cheap internal support. I’ve been surprised at how fast I can plow through plates, almost as fast as bricks. There’s a lot of yellow plate inside that observation platform.
I’ve ordered from Plastic Bricks Direct before and they’re on my short list to order from again soon. I’ll have to wait til next month though, I already made one largeish BrickLink order this month.