I have a 2006 Chevy with the 6.5 short bed. My 5th wheel is a 2004 that does NOT have a radius style front. I do NOT have a slider hitch and so far have not needed one.
That all being said if I need to replace my hitch for any reason I will probably get a slider hitch. My current setup was done by my dealer with no input from me. At the time, it was my first RV and hitch and I knew nothing.
I added a Blue Ox Bed Saver system to my hitch and I also have Emergency Road Service. I have not used either one as of yet but the peace of mind they provide is worth it to me.
I would perform the measurements specified above and if it is close go with a slider. As stated before, better to have and not need then not and find yourself in trouble.
Best of luck to you!