Still Pedeling - Is your bike configured as fietsbob describes? I can't imagine that that adding larger diameter rolling wheels would make much of a difference. Also adding an extension of some kind to the handle bars seems impractical and a hassle.

When I use mine in shopping cart mode I usually have the handle bar folded and pull the bike by the handle on the t-bag. The height is very similar to the height of the configuration described above, pulling on the handle bar. It would seem easy to rig a little stiff loop extension that could go through the bag handle and extend up to your reach.