It's not the launch to worry about, it's the pickup. the weight can be a challenge, just carry a bag of kitty litter for traction!
My motor home makes about 500hp (injected 468) and I've never had a traction issue, you do gets some funny looks though. I normally back down the entire ramp, it's a pain in the ass to turn around.
One year the water was way down, I had to back down the ramp about a mile (not exaggerating).
Make sure your emergency brake works perfect. Have a chock or two handy.