Marketpress Product Entry Customization

I'm creating a multisite and would want to make sure that site owners are including certain details of their products such as the dimensions and weight when they create a new product. I'd also like to remove some of the current details listed.

What are your thoughts on the best approach to do this?

1. Hire a developer modify marketpress?
2. Write a marketpress add-on?
3. Any other ideas?

I'm concerned that with either #1 or #2 above, if there's an upgrade to marketpress, that the modifications will become broken.