It is going to cost a few bucks to have the inverters wired in. Besides the cost your biggest concern will be finding someone who has the proper knowledge and design competence to integrate two inverters into your system. To do the job right you will need a large capacity battery bank (400+ AH) for the kinds of loads you appear to be anticipating.
Chuck - Sparta, TN
2012 Jay Flight 22FB, 2 x Honda EU2000i
2013 GMC Yukon XL Denali AWD
EDUCATION is what you get when you read the fine print.....
EXPERIENCE is what you get when you don't.