Do you have a DC8 (legacy AC3 power strip), or do you mean EB 8 (Apex EnergyBar)? Big difference between the two in some ways. I ask because some people here on the forum tend to use DC8 as a generic term.
DC8 - officially, the limit is 10' IIRC, but people have used twisted pair cables to go quite a bit further.
EB8 - custom USB cables can be obtained which work fine for AquaBus connections... a number of people are using 50' & 100' cables. Officially, the total max combined length of all AquaBus cables is 200';