I'll try to field this one even though it may not be the best answer ever.
Maintainers do not "sit in a hangar all day". Here's a quote from something I posted a long time ago about the diverse jobs you can get with a maintenance contract:
Even with an assigned OccField, the subsequent MOS's can vary so that the working environment and hours of one MOS may not resemble any others within that field. For instance, let's take avionics (my field). Within the Avionics OccField, there are an abundance of individual MOS's. "I-level" MOS's (64XX series) generally work from 7am-4pm (roughly) Monday-Friday, unless there is a large-scale exercise or deployment (more on that later). They work inside most of the time, and do not do as many deployments. "O-level" MOS's (63XX series) work anywhere from 8-16 hours days, 5-7 days per week. They work outside all the time, get dirty every day, and deploy more often. Much more often. Even within the same MOS, from duty station to duty station, conditions vary. Someone assigned to or supporting a training squadron will not face as many deployments as someone assigned to or supporting an operational squadron.
Same goes with pretty much any aviation maintenance MOS. You may get a 'cushy' job that doesn't require much time outside. You may get a different job that doesn't allow much time inside. Unless you enlist for a specific maintenance MOS you won't know until you're at MCT (is that still when they assign MOSs?) what you'll get. And even then, the people at MCT probably won't be able to tell you what a 6060 (or any other aviation MOS) is or does.
On to 7242. I was never one of these but I have a good friend who is a 7208 who told me a little about what the Marines do. This is the part I may screw up but I'm going to try anyway. Working in air support, you will probably be assigned to a DASC (direct air support center). It's kind of like a tactical air control center. No positive radar control, though, everything's done with maps, grease pencils, and position reports. Lots of sitting in the DASC (which is usually in an enclosed box due to all the high priced equipment and high security required to support what it does), talking on the radio, plotting on maps, processing air support requests, and the like. To me it actually sounded interesting but I love technical jobs like that. They do spend time in the field but I don't know how much.
From the MOS Manual:
5. MOS 7242, Air Support Operations Operator (MGySgt to Pvt)
a. Summary. Air support operations operators perform duties incidental to the operation of tactical air support systems, operating various electronics equipment in a clear and electronics countermeasures environment, performing liaison necessary to ensure effective air support operations, and supervising and participating in preparation, movement, and emplacement of air support equipment.
From what I know about maintenance and what I've heard about air support, it sounds like you stand to spend a lot of time sitting inside as a 7242. Of course, if you get an I-level MOS the same thing applies. So, take what I just said, think about it, and try to figure out what's best for you. Good luck.