Excellent idea,
563; I hope you won't mind my contribution of an idea for a pedal bracket that can be made for just as cheap.
What is needed is a thin, strong piece of material to act as the bass drum hoop in this case. It would need to also be as secure, so attaching to the very cradle itself is required. Portability isn't to be comprimised either, so this secure apparatus must also be easily disassembled (and reassembled) in the interest of transport.

This staged photo displays the parts needed: the dish rack, a 2 x 12" or thereabouts piece of wood (perhaps a scrap of moulding), and a T-strap or similar piece of thin metal—these are usually used in the framing of walls. These usually come with holes predrilled that will be useful later on. The latter two parts should be easily obtainable at a home store.
When using tools, be careful and follow all safety precautions.
First, bend the T-strap at a right angle as shown in the photo (a vise or careful hammer-pounding [using a curb or step as an anvil] while standing on one end may be needed). Using this as a gauge, stand the bent T-strap up with the small side facing upward in front of the dish rack. This can be used to gauge the height at which the piece of wood will be attached; ultimately the strap should hang 1/4" or so above the floor so the pedal has room to attach underneath.
The neat way to do this would be to drill one hole on either leg of the rack (similarly spaced holes can be duplicated on the piece of wood) and use bolts and wingnuts to facilitate easy dismantling. For a more permanent solution, plain old wood screws can be used to anchor the piece of wood at the proper height.

Then, we attach the bent T-strap in this manner. A bolt and nut would work best with this step. Make sure it rests just above the floor as mentioned.

So, if a little thought is used besides my admittedly limited guidelines, you should be finished with your new bass drum cradle complete with pedal bracket. It should be sturdy enough to handle the usual force one would use when playing a drum that would fit in such a cradle.