Some jobs seem to only want you around for your experience/expertise, like baby-sitting and preventing fires. You could theoretically make everything so stable that when something fails a secondary system kicks in, and all you do is to debug when that happens and make it even more stable. Just make sure you have an excuse to not work on site or they will keep you busy with meetings, admin, and reports. But one day there will be the the perfect storm and all systems on your 15 different full time jobs will go down. You could always call in sick that day, but then they would hire more ppl like you.