Alan, i recently read on a different forum that one of the reasons the bases chafe is because latex, silicone and rubber are inherently sticky materials. on top of that, most water based lubes also get sticky when they dry, adding to the discomfort.
they suggested that one should switch to glass or metal plugs. (preferably the ones with a hole through them for prolonged wear)
now having said that, i have a metal one and that one becomes even more uncomfortable to a point where it actually hurts, mostly because it's rigid.
so in conclusion, we face a dilemma. soft materials get sticky, water based lubes gets sticky and we can't use silicone or oil based lubes on said materials anyway. AND on the other hand, rigid materials become even more uncomfortable after a while...
i've said this on here before, but the one that does work for me is the tantus infinity plug... i've tried that over long periods of time and it was ok. there was the occasional pinch of the buttock, but generally no major or unbearable problems. (other than having a sore ass but that is the slave's problem hehe)