Look, you're really the only person who will know the answer to this question. What works for you kid may not for another so asking an answer like this, as you can see, is bound to give you many different opinions.
On 'technical' merits alone, if your child is only 48" with some big shoes on then I'd be more apprehensive. My daughter - a skinny little thing - was a smidge below 48" when she first rode RnRC but they let her on anyway and she
loved it. I hadn't ridden it in a long time and forgot just how much the ride can jostle you around (I'm not saying it's terrible) and with her build, I'm not sure if I'd have let her ride it again back to back. Luckily I didn't have to tell her no; a new CM was manning the line when we came back through and he wouldn't let her through, due to height restrictions, the second time and that was that.
The thing about rides when there's a question of "should I" is this: you can't un-do it. Say your child rides the ride and loves it. Cool! But if he/she doesn't, it may sour them on that ride... and possibly others ... for some time. For example, my DW and I coerced our DD to ride ToT when she was 4 and it took nearly 2 years for her to ride it again thanks to the literal terror she felt from that first ride (though she still loved riding BTMRR and other rides during that 2 year stretch). That was my fault. She wasn't ready for ToT and I shouldn't have convinced her otherwise. Not a proud Dad moment for myself. Had we waited maybe another 6 months or a year then I'm sure it would've been fine. Now, she's totally over it and loves to ride ToT but she absolutely wasn't ready for it on that trip.
So, again, it's really your call. I don't know how your kid would react based on the ride itself but based on the height concern I'd wait. But it's your call.
As an aside,
YouTube is a great resource and can give the kid an idea of what to expect which will help lessen their anxiety (if there is any) and should make the experience more enjoyable.