A skimmer rated for a 100 gallon tank, will barely be able to handle a 100gallon tank, Skimmers are highly over rated. They are figured on very low stocking figures. If you can't find a HOT skimmer rated for at least a 200 gallon tank, then you have two options,
1. put 2 or 3 skimmers on the back of your tank, not pretty. or
2. Set up an overflow box and put a sump under your tank, then you can use an insump model.