It is generally recommended not to free-feed rabbits. I’m great that it’s working for your rabbit however it’s really not for every bunny. Some rabbits just don’t know when to stop and will simply just eat as many pellets as they can throughout the day, ignoring hay and veggies. In which case, if a rabbit can’t control what it eats, you will need to ration out food. I’m yet to meet a bunny that could ration it’s own food to a healthy degree, they just don’t have the mindset for it. In which case I really don’t know what to suggest in terms of helping you meet your goal of free feeding.

Rabbits should always have unlimited hay. Unlimited pellets will probably make most adult buns over weight, so I wouldn’t recommend that. But you can very well experiment, just start slow. Bunnies’ tummies need time to adjust to all dietary changes.
You can weigh your buns weekly and make a weight-diary. I weigh mine in a bowl on my kitchen scales. I find it useful because a bunny’s weight loss or -gain is difficult to see. It’s like they’re always wearing loose fitting pajamas.

Now, I had my Jessie for 8 almost 9 years, and she was always free fed. She would also pick veggies and hay over pellets. I can’t free feed my current bunny, Monte, pellets. She’ll just keep eating them. I can free feed her veggies though. She’ll only eat what she wants. I think It might really depend on the rabbit.

I recommend reading the nutritional information that comes along with a bag of pellets. Some pellets contain molasses/corn syrup. This makes them high calorie.  I think these pellets are intended for buns that a caged and fed only pellets.  If your bun is eating hay, green veggies, and fruit treats, you bun doesn’t need high calorie pellets.  Actually, they don’t have an absolute need for pellets…IMO.  I buy pellets that are essentially ground and compressed hay/vitamins/minerals. They have bowls of these pellets just in case they get the munchies during the night. My buns are very adequately fed!  If we try to sleep in on the weekend, they are scratching and banging on the bedroom door for us to come out and give them their expected morning treats.