Not much of an issue, that s how I wired mine up in my '90 10yrs 13yrs ago, and I haven't had any issues with it set-up that way. The last time I had it at the dealer, a tech thought that my 3.0 might run too cold with the fan on constantly, but my gauges show that it is only running a little cooler.
If you expect to do water crossings with it, you could put in a ground interrupt switch under the hood. This way you can turn it off to cross water, and not have to worry about it being accidentally turned off in the cab.
