I use
Garmin BaseCamp which I really like.
This is designed to be used with Garmin GPS units but it is a standalone program and free.
I use it in conjunction with my Garmin RV 760LMT which is a GPS made for RVers.
On my system BaseCamp does have an RV routing mode. Select the Edit->Options menu item, then Activity Profile. I select the RV option and can enter my RV attributes height, weight, length etc.
I am not sure whether the RV profile is a standard part of BaseCamp or if it was triggered when I connected my RV 760LMT. As it is a free download you could try it, see if the RV option is available.
I use BaseCamp to plan all my trips and then download them to my GPS.