Put it in perspective. There are around 70 tornado deaths in the US per year. There are in excess of 35,000 vehicle deaths in the US per year. You are in far more danger in driving thru the area than by tornadoes while in the area. And the months of April, May, and June are the prime months for tornadoes primarily beginning in the southern states early and moving northward as the weather warms. So April will be sort of a "shoulder" month in the great plains.
Tornadoes are very destructive and life threatening, IF you happen to be in the path of one. But they are not something that happen daily, or even weekly. They are typically very scattered, short lived, and cover a short distance before they dissipate. I have lived in the southern end of tornado (north TX) all my 74 years. The last time a tornado hit our house I was 3 years old. And none particularly close since then.
Don't be overly concerned about them. But do be prepared. There are weather apps for your smart phone that will send out warnings for the local area. A good NOAA weather radio is good to have. You can program in the local county you are presently in. If strong storms are predicted, stay tuned to local TV channels for up to date weather forecasts. When you check into an RV park find out if they have a shelter on site. And if not, where is the nearest safe place to go.
Again, be prepared. But don't let that worry spoil your trip.