Hello Mr Fire, You know wt,  i may be completely wrong. I did my co-op for a year, my employer would not let me work even 21 hours. I was instructed by school official to quit my on campus job or not to exceed more than 20 hours combining co-op and on campus shit. You know what else, they may be wrong too. Why dont you ask ISA to issue you a letter stating that you were authorized to work 40 hours, you can use that if anything shitty happens while coming back.I really dont think you will have any problem coming back in either case, unless you have a pending criminal case ni american courts, obviously u dont. Aight brother, itz your call now. Once again, JUST BE CAREFULL. You have invested too much in this country to make any unnecessary decisions.