here is a little secret to doing ANY quilt that takes HST's in large amounts.
look at your layout..now make a B&W photo copy of it and do it in smaller sections...like 4 or 9 blocks at a time...pin that on the wall and do the next section, etc..then connect your sections the same way..like if 2 sections make 1/2 the quilt you do those 2, then the 2 belows that to make a 4..etc...make it so much easier to go together and if you do have unstitch to realign a few, it is much easier than removing the entire ROW to get to the middle...