Well, that's encouraging...just the fact that you have tried. And I admire the fact that you are trying to learn something new with the full cuts. But just let me say, anyone can get a pair of full wellingtons together (especially with soft, stretchy leather) but really controlling the boot--how it sits on the last, how the side side seams lay, the tightness of the boot around the top of the cone, etc, while making a boot that will last and look good--is no walk in the park. You have my best wishes.
Again, if you can identify specifically where you are having problems, I'll try to help. But you know me...I tend to get serious about these things and I don't want to bore everyone to death...OR...write the book on line, either.
If you haven't already, check out "The Art and the Mysterie" discussion. And if you are a member of the HCC (info coming) or even if not, there is a video of me crimping some two and a half ounce veg calf liners that was made at AGM a couple of years back. It's available for a small fee from the HCC--a non-profit organization for those who are worrying.
Oh, and by the way...two tips...always crimp your fronts inside out. Full front boots need to be "boned" and "wrinkle chased" extensively and that protects the finish. After they've dried and taken a "set" then re-seat them on the boards, spritzing them liberally, right side out and let them dry out, again, for another couple of days.
Also, (and the video shows this) very often, especially with chrome tans--like the kangaroo--you won't get the leather tight to the board and clear all the wrinkles until almost the last second. My point is just that maybe you gave up on the 'roo a little too soon. Been there, done that, bought the T-shirt.