Illustration Work with Relaxed Deadlines?

I was wondering if there's any particular kinds of illustration jobs that tend to have more lax deadlines? Say book cover illustration for instance (especially fantasy, sci-fi or adventure stories)? or pen and ink vignettes? Even though my main focus is my own projects, I am interested in picking up some client work here and there if I can get it. Since I currently have a small leather goods company and a web dev company (both of which are fairly flexible), I'm mostly only able to do art on nights and weekends, so working on projects with tight deadlines just isn't desirable or at the very least, more stressful than what I'm hoping to take on.

Is this realistic to try to build a side career in art like this, or more to the point, assuming I put out good work, would it hurt me in the eye of clients to not be pursuing full time illustration work?

EDIT: I should clarify. I don't mean lax deadlines as in missing deadlines, but more so long deadlines—projects with plenty of lead time.

smceccarelli

I don’t think it´s unrealistic to try and get illustration work even if you can only work limited hours. When you have more time you just end up working on more than one thing at the same time, so if you limit yourself to one project at a time you shouldn’t have problems. There’s no „category“ of projects that tend to have longer deadlines per principle, I believe. The wisdom goes that book covers are given more time, but the only one I’ve been offered so far had a one week deadline. Educational tends to have shorter deadlines, but again, I have one project now with a November deadline. My experience so far is that you can definitely negotiate deadlines just as much as you can negotiate money, and in most cases there is a lot of flexibility around timing.

@smceccarelli That's good to hear, thanks! Over time if I can shift more towards the art I'd happily do it, but its good to know that its possible to start like this.