Pulling movements in general are pretty hard to do with just calisthenics. Anywhere in that big park, is there a nice sturdy pole or post? If so, you can get an elastic band set, usually very inexpensive and portable, and use that to do rows (and face pulls, if you want).

I would also try to incorporate pull-ups (some parks have pull up bars, or you can install one at home) to work your lats. This might be tricky if you’re not at the point where you can do a body weight pull-up yet. If that’s the case, you can probably figure out how to do a lat pull down with elastic bands and the right kind of rigid surface.

You can use your feet to stabilize the bands to do curls (biceps, some forearms) and shrugs (traps) to round out most “pulling” movements. Also you can isolate your triceps and side delts with bands. And do “harder” ab exercises than just sit-ups. They’re very versatile, like a much less expensive cable system.