The Noise Tool from Intellijel is perfect for what you want. It includes a sample & hold circuit. It's normaled to the white noise section but you insert your own source and triggers. It also has a built in clock that can be set to random triggers as well. It has plenty of features and is as non-menu divey as you can get. I believe you have space for it in your 1U row. I have one and it's a very useful utility module.