A plain ole hair dryer will give you the same results as a heat gun, just a bit slower. We had to replace the rear graphic on our "07 ROO HTT and I had it done in 20 or 30 minutes, cleaned off with Goo Gone, rinsed and ready for DH to apply the new one. That said, my cousin's DH in Houston removed all the striping and decals from their '03(?) KZ with the aluminum siding and it was a PITA. Don't know of the siding made the difference or just the age, but he picked striping specks forever before it was done.
If you replace them yourself, handy hint is to wet the area first with a solution of a bit of Dawn and water, then peel off the backing on your decal and the water gives you the time and ease of getting it lined up just right. Then very gently squeegee the water and any bubbles and let it dry. FR didn't tell us this, just to peel the backing and apply. DH was concerned that it wouldn't line up right and then remembered when we applied the name graphics to our boat, those were the instructions. Works like a charm and has no effect on the adhesive on the decal....just makes the job a LOT easier. If the new decal does not come with a squeegee, head for Lowe's or HD and in their wallpaper tools section you can find a small - maybe 3 - 4" plastic smoothing tool - and that'll do it.