For those who have the equipment, the 'flow over' stripping process is much preferred. I don't know anyone dipping furniture anymore for the very reason you describe, not to mention loosening of glue joints and raising the grain. The process has bleached the color from the wood which has to be reintroduced by staining. The problem you have now is that the surface is sealed because tung oil contains additives designed to harden it to become a hard finish. This must be removed in order to allow the wood to accept the new color. Depending on how tough the finish is, this can be done with methyl hydrate or failing that, lacquer thinner or failing that, acetone. After sanding, it's now ready for staining. Try a very light color first to test for even absorption. If it's uneven or blotchy, then not all of the finish (tung oil) has been removed. As far as 'pickeling' is concerned, since it is an opaque finish, you will not see the wood color anyway. The only consideration might be the openness of the pores which is desireable for a pickeled finish.