My advise would be listen to actual professionals who've used DSLRs/Mirrorless in these and even worse conditions.
Not all DSLR "have some type of restriction for long shooting because of heat". Some DSLRs have heat issues, others do not (including cameras like the URSA).
A restriction some DSLR's have is a 29 mins limit for continuous shooting -- which is something entirely different, and done for tax purposes (so they are not classified as video cameras in Europe and get a higher tax rate).
Seriously? "a camcorder"?
It's 2016, we have been using DSLR and mirroless video for TV/Documentary and even feature files for almost a decade...
Yeah, it's not meant for Americans.