what kind of issues could i run into if i ran httpd on more than one port and the other port being something other than the typical 80,1080,8080 etc?

I've got clients that are blocked from the standard http ports and were looking for a way around them. I realize that if someplace is blocking the http ports, the other ports are probably not available either, but I thought I'd see what i could do for them.

if there are no other problems, would just adding the port number to the httpd.conf Listen port list and including it in the firewall exceptions be all I need to do?