Stripit .. On THIS motorhome, I used a vinyl SLITTER ( essentially a lathe with a mounted knife cutter ) to cut the stripes to size ( i.e. 1" - 2" 8" ) and then cut into 4' - 6' sections .... overlapping them down the length of the motorhome , to avoid a large SAG in the middle.
The overlaps really just blend in and are not very noticeable.
On the larger curves ... it is close to impossible to recreate the exact archs , so I use a large ( 24" ) piece and position it to cover the whole section, on an angle .... use VERY soapy water on the sticky side, and squeegee out that same water ...then ... CAREFULLY use an exacto knife to cut , just outside of the lines showing through. NOW to cover any irregularities in the cut , I use 3/4" to 1" VINYL as rather large PinStripes and even out the flow of the curve.
THIS can be tricky also, but after a few mistakes, the technique becomes more apparent.
While I have , in the past, stripped off the whole graphic, which makes some of this easier, since you can create your OWN swoops and down-turns, however, the damage potential to the fiberglass really becomes a problem without a good solution.
I tried the body filler idea on a 38' Newmar I owned once , and found it made MORE of a disturbance than NOT using it. Then again ... I am not a paint & body man so perhaps my poor talents were to blame.
If you have a $80,000 motorhome, this is not a DIY project that I would suggest..... but ... otherwise, it makes for a great facelift that can make you a bit more proud of your RV.
Hope this answers your questions ...Richard