I just recently put on a set of those same sponsons on and I felt it was remarkably easy. First get 4 bolts per side then pre drill the holes toward the bottom of the sponsons( about 1-1/2) inches from the bottom. Space the holes out evenly but i put one close to the front and one close to the edge on the rear with the others spread evenly. Countersink the holes deep enough that the heads sink in and leave enough of a lip to seal with 5200 fast cure when done, be careful not to go too deep though or you'll be holding nothing but foam! kind of find a happy medium. Next if at all possible measure your hull and put pencil marks so they are even on both sides front to back. I found my mounting position by having a friend hold up the rear of the sponson while I was at the front.
I then slowly pulled the sponson until the apex of the bottom of the sponson was in line with the bottom contour of my hull. All the while you need to make sure the top of the sponson is against the top of the bottom deck (up as far as it will go) trace the line where teh very front of your sponson is.
hold the front of the sponson while your friend drills the first hole into your hull. Insert bolt one. Hold the sponson in place while your friend goes back to the rear of the sponson and does the same to the rear hole. Hold sponson tight against hull while you drill the other 2 holes .
Remove sponson, slather with a decent amount of 5200 fast cure and reinstall sponson. I found it easiest to leave the bolt in. it helped me correctly re-align the sponson to the holes. affix nuts with washers on the inside of the hull and snug the sponsons. DO NOT over tighten or you will pull the screws through the countersink. the 5200 is more than capable of holding these sponsons on the bolts are for added security. take a dremel and cut off the remaining portion of the screw on the interior of the hull so the nuts are as flush to the side as possible.
Repeat on other side of the ski. You can do it in one day but the 5200 should sit 24 hours technically to cure. MAKE SURE TO USE 5200 FAST CURE OR IT WILL TAKE FOREVER TO CURE!!!!! BTW I really like my zero sponsons.