The clay should remove the wax...but...just to be safe I always wash the area with Dawn dish soap (then wax surrounding areas soon after avoiding the vinyl edges).
My best suggestions after having done a LOT of large vinyl installs is to:
Have a helper who's in for the long haul, don't be in a rush, find a good place free of wind & in the shade, use the hinge method (use tape to keep the pieces aligned), measure several times especially when doing the sides so they are relatively even, take your time & use plenty of wetting fluid, do it when you are in a calm & patient mood, if it looks like you've messed up calmly try to repair what you've done. 99 out of 100 times you can fix it (Tim & I have had our share of mishaps & we've managed to fix nearly all of them to be practically unnoticeable & I am an EXTREME perfectionist).
Make a soft side on one of your hard car installation tools (plastic squeege). I used some spare felt (you could also use T shirt. I folded several layers over ONE side & duck taped it on. This is used on the flames AFTER the carrier tape is removed (if you have it), and to smooth out extra fluid & bubbles. Have a VERY sharp fine tipped needle handy to pop bubbles after a day or two in the sun.
These tips have served me well. I hope they help you too.
GOOD LUCK!! Your flames look relatively small & easy to handle. You should do just fine. I've had 3 sets of large vinyl flames over the last 8 years. The most important advice I can give you is watch the vinyl's finish. If it dulls & discolors, or looks grey & colorless REMOVE IT ASAP. Removing damaged vinyl (powdery grey or cracked) is a true living nightmare. Removing old but still relatively decent condition (dulling w/out heavily faded spots) vinyl is a walk in the park. No problem whatsoever.
Here's a pic that shows the soft sided squeege I was mentioning. The hardest part of this installation was aligning the hood pieces. I think that alone took us over an hour. We got them within 1/8 inch though. Not bad for amateurs! lol
