Would you recommend avoiding PICC line placement in a kidney transplant patient with an estimated GFR of more than 45 ml/min/1.73m2 and no functional AV access?

Great question and of course there is no data to guide decision-making in this scenario. Anecdotally, I would assess the patient as a whole, not just limited to current GFR though that is a great starting point. What is their age and co-morbidities - is this a younger /middle-aged/older patient, is ...

A good option, if a PICC line is necessary, is the placement of a tunneled internal jugular vein PICC line.

By using the IJ vein, you can preserve peripheral veins for any future AV access placement.