Yeah, but the MMU didn't have very much delta-V. The smaller emergency jetpacks they wear outside the ISS have even less. And you can only stay in that suit for so long. For transfers to other vessels in diferent orbits you're going to need more delta-V, which means you want something with chemical reactant jets on it, probably hypergolic, as opposed to the very low Isp of the MMU's cold gas jets. That means a larger structure with bigger propellant tanks and some safe distance between the astronaut and the nearest thruster, at least a few feet. If he must ride inside his suit, then you should have a life support system on the vehicle that he can plug his suit umbilical into for air conditionaing and to preserve battery power. He also needs a way to control the vessel without removing his gloved hands or vision-restricting helmet. Anything else? Maybe a retractable sun shade made of mylar or something. Also you need to decide how many passengers this thing will carry and for how many hours. Decide how electrical power will be generated, probably solar, and determine how much area the panels require for your chosen solar cell technology, and put them somewhere, maybe on the dorsal side. These could serve as the sun shade perhaps.
Shouldn't be too hard to design a basic version once you settle on the requirements.
