Hi Becky,
There are always lots of discussions about harnesses on here, I personally think they're fine and use them on my house buns sometimes. I have recently adopted a french lop called Darwin and put him in a harness for the first time a week or so ago (I don't have a permanent run in the garden) and thought he might like some fresh air as he was an outdoor bun at the rescue centre). He wasn't bothered by it in the slightest, and obviously I was on the other end of the lead so he wasn't ever going to get himself into trouble like people often suggest on here. Its down to personal choice.
I assume you'd have to pick him up even if you were going to put him in a run so whatever you decide with harnesses you're still going to need to pick him/her up.
My other bun, Lavender (not a french lop but almost the same size) hated being picked up to start with but they need to learn as you'll have a nightmare if they get ill (as willowholly says above). So, I forced Lavender to get used to it. To start with I picked her up every other day, then literally just put her down again and gave her a treat. I gradually increased how often I did it and how long I picked her up for. After a few months I was picking her up every day - having a look at her eyes, ears and teeth (just to get her used to me doing stuff to her). Now, she's fine, I pick her up whenever I need to (vets, medicine, eye drops, garden etc) and she doesn't kick. She doesn't like it though, she's just learned that it has to be done and she's not going to get hurt, so she always stamps her feet when I put her down, but then she stands on her back legs cos she knows she'll get a treat.
I hope it works for you too, good luck.