Here are some options to do this:
We can set up a white-labeled subdomain of your web address (e.g. yourchoicehere.yourdomain.org) that would open up your Flipcause campaign. This would be an additional cost of $100/annually and would take a few days to create. See this Help Center article for more information on White-labeled custom domains: http://help.flipcause.com/help/white-labeled-custom-domains
We can set up a custom subdomain of Flipcause (e.g. yourchoicehere.flipcause.com) that would link to your campaign page. This would be an additional $25 one time and take a couple of days to create on our end.
You could use a 3rd party site like tinyurl.com to condense your URL. This is fast and free, but has less flexibility.