Rosie,
When you say feeding tube, I'm assuming a g-tube. In that case what kind of button do you have?
There are several types, and some are a lot smaller than others. It might not be perfect (sorry), but the right button will go a long way to making it a bit easier.
Examples are the Bard which is quite flat, but has to be put in at the Dr; and the AMT mini which is a small one that looks like a Mic-Key (most common) but is a ton smaller and easier to cover.
Hope this helps,