CGR,
I haven't made a paste. That sounds like a good idea. When I butterfly the bird, I sprinkle form a distance above. When I rotisserie, I sprinkle while the spit is spinning. Those work well and I get a nice even coverage. This beer can is the problem child. If I sprinkle the chicken chicken while laying down, when I pick it up to handle the bird and stab it onto the can, I smear the rub. I can't tilt the nearly full can to sprinkle once he is stabbed. The bird is smaller at the waist (does a chicken have a waist) so I have to throw up under the breast. This finished rub is a very fine powder.
Your idea might work to add the oil to the rub and then paint it on with a pastry brush. Think about it and let me know what you come up with.
A good alternative is to butterfly the critter. It smokes nice, cooks even, fits on a Bradley rack, and presentation is nice. I do, however, like the aromatics in the beer can.
Thanks for the idea,
Good luck and paste it up,
Pachanga