Yes get a tailwheel endorsement. You have to. There is no min to get the endorsement, it is not a rating. There is no written but there are a lot of great books and video instruction sources. TW endorsement might take 2 or 5 or 10 hours of dual, depends on the pilot. If you are going to check off an insurance requirement or rental min that is another matter. Unless you have 100's of hours of TW time, you will pay a premium. They may require transition training in specific model of RV. However if you can fly a Citabria, Luscombe, C170, C180 well you can fly an RV well.
I can say RV's are tame taildraggers, like a fast Piper Cub. However as an instructor, I found if a pilot can not land well in tricycle gear plane crosswind or not, it will not get better with a TW plane. If you can land well in a tricycle gear plane, your transition will be much easier. After I got my Pvt long ago, I found every chance to fly in crosswinds and perfect my skill. Some pilots are afraid of crosswinds.
Regardless of insurance you need to think competency and safety. Can you land a trike plane in strong cross wings well with complete control authority and confidence? Do you know the difference between Fwd slip and Side slip? Regardless of insurance get current in any plane. Then get TW training and the endorsement. I recommend Riggin Flight Services Madison, SD, based on the review below by Juan Brown. They have a boarding house that is very reasonable. Go and immerse yourself in TW planes for a week, from people who have been flying them for a lifetime. Don't do it to check a BOX, do it to be a better pilot. Don't get an endorsement get competent.
https://www.youtube.com/watch?v=8-ew-8yp8-0
Last is insurance, it is not a legal requirement you have insurance. However if you ball it up then it is on you. Not saying it is wise to do this, but I have owned and flown planes without hull insurance. However I always carried liability. In other cases I carried only ground not in motion hull insurance.