are you talking about this:3proxy can do this. You need to create access control that allows your connection through and chain it to a group with your list off 100 proxies. 3proxy will rotate randomly through your list for each connection.
You can install 3proxy on a ubuntu server. Read the config file it has instructions. Aside from regular setup, look for commands 'access' and 'parent' for creating the backconnect proxies with rotation.
Not trivial to do but also not that bad either.