Is it really full plate if it's on a Halfling? Wouldn't it be half plate by default?
If you give Half-Plate to a Halfling then it's just quarter plate.
Ever since I got some perspective on just how small and light a halfing is (having two kids), I just can't take the little things seriously any more. At least LotR hobbits had some heft to them. Something that small in plate just can't have the muscle mass to move full plate around.
Nonsense.
A well-made, custom-fitted full plate harness wouldn't encumber a halfling any more than an adult human sized armour encumbers an adult human.