If you want to do it, go ahead, the most used 5/3/1 rep schemes (like original 5/3/1, 5’s Pro and such) work well for other movements too - I remember an old article by Jim where he’s asked about it and he said he used them for power cleans and barbell rows too with good results.
For carryover, it depends.
I don’t think romanian deads have that big carryover in regular deads to the point they can be a substitution. Romanian deads usually help the lockout portion of the lift, much like straight leg deads help the initial push from the ground. They fit in the assistance stuff, single leg/core category.
You can do them and program them in 5/3/1 fashion but don’t expect them to actually improve your full deadlift unless you’re specifically weak in the second portion of the lift. And even them, I’d do full deads first and romanian deads after as supplemental (5x10 FSL, for example).
Regardless of what you do, if you’re training 3 times a week there’s plenty of great full body programs in Forever, you do each lift multiple times a week (properly scaled to be sustainable) and it lends itself better to substitutions