A condensing unit for outdoor kitchen is just as important as a full sized unit for indoor kitchens. You need to make sure that your portable units are going to be sturdy enough for the additional weight of food that you are going to be cooking and storing for your outdoor meals. There are some companies that have gone to great lengths to ensure that their portable units are as efficient as possible.
Your a unit is going to be able to heat up water and keep it hot while it is sitting in the ic pan. You will also be able to place your ic in the holder that has the stand that you can connect to the tank of water that you will be using for your outdoor cooking. This will help to keep your food warm for much longer than you would be able to if you had to use the icebox. This is one of the main reasons that people choose to go with portable ic units and it stands instead of using the iceboxes for their ic.
Another thing that you want to keep in mind is the fact that your ic unit will be cooled before it is heated up. If you decide to place your ic on top of the house it will require some insulation, but if you use an ic stand for outdoor use it is going to take all of the heat out of the air as it sits on top of the stand. Make sure that you are checking the insulation level of your it stands when you order your ic units for outdoor use.