High speed taxi tests are unnecessary and riskier than just flying the thing without training, not that I'm advocating for that. Lots of people have crunched their airplanes doing high speed taxi tests thinking it's a good way to "ease into it".
Yeah - let me emphasize this. High Speed Taxi testing is really for brand new designs - not aircraft whose designs are proven already. This is because a lot can go wrong in a hurry, including premature liftoff…and now you’re flying! In fact, properly controlling an airplane during high speed taxi is a more difficult task than just taking off, flying, and landing the airplane.
I ask the original poster’s forgiveness if he is already a very experienced pilot - we don't know your background, so its kind of hard to recommend what you need. If you’re experienced in many types of Experimental aircraft, then you’ll probably have little trouble with an RV-3. If you don’t have a lot of time in light, sensitive, high performance planes, then yes - wait until you can get some good instruction in a two seat RV, then go fly the -3….its not difficult at all to fly, and pretty well mannered - you just have to be ready for the quickness.
But I’d suggest that you stop high speed taxi work until you have at least flown an RV with some good instruction - and then just go fly and enjoy your -3.
(And to directly answer the OP’s question on “what did I do”, I had flown many different types of high performance taildraggers, so after talking with several experienced -3 pilots about any potential problems, I simply went and flew it - but then, I was flying several RV’s several times a week.)
Paul