Hope someone can help Electrical Issue

[Dexter]

My 99 8362 has a 1000 watt inverter charger made by heart Int. I want too increase my battery capacity. Add 4 golf cart battiers to the two deep cycles already in. Can I add wattage by adding just an inverter (much cheaper than a new inverter/charger) Also will mixing the battiers cause a problem. I could still add capacity with just the 4 cart batteirs. Can anyone advise me about the electrical issues that will come up.