If you *really* cared that much you would just come up with features and predict with a ridge regression. Use basis, open interest, historical decay, AR(X) forecast, and then fit, make sure it’s robust OOS. Funding has strong regimes, this is worth modelling.
Not going to drive much PnL for most books but if running a large funding book it is worth it for what is realistically < 1 weeks work
It follows an auto regression process - you can fit a recursive AR (X) model to forecast funding out. It’s fairly easy and beats an EWMA of funding. It’s not the biggest of questions to answer in quant finance but nonetheless it’s an easy incremental boost