Many years ago when i was doing birding, locally we have to walk about 4km total say at Sungei Buloh. My gear is about 9kg total. Some folks might be up to 15kg or so. A 600mm f4 is 5kg, secondary 70-200 f2.8, 2 bodies, 1 tripod with gimbal, bag, flash+flash extender. Water bottle and maybe food. In Malaysia, treks of 10km is pretty common to get the "good stuff".
You even run with that gear at F1, for those pros.
When i was younger, my wedding gear is 11kg total, day in day out during peak period 4 days in a row, 4-6hours of sleep each day. Finish already go back to regular day job. But then one fine day I overworked myself and landed in hosipital for 5 days so i won't recommend you to try that.
Of coz this is a hobby, not a triathlon.
How to counter that? Easy,
body build + cardio.
You finished a 24km march with ~12kg right. Some can finish 36km with 30kg...but those are pros!
Why that time can do that?
That said, my astro gear is relatively light (compared to other setups) but getting old already. 36kg total, but limited to 100m walk. After that hae hae chuan liao....getting old approaching 40s. Sigh...
That said, i'd prefer that you save up and get something bigger. Else it might turn you off with the "That's it?" syndrome with the skies here in SG. Seriously if i have the space and logistics and ob area, i will surely whack 16" minimum. Above 20" it tends to get more ex exponentially. See tourist objects like Carina/Jewelbox/Saturn also more shiok.
One of the big plusses if aperture is an issue is with video assisted astronomy. You can check that out on CN.
Before you start off, take your time and read the forums. That said, with 500 bucks, you can definitely enjoy astronomy quite happily with a pair of 20 x 80 binos or 25 x 100 (both 4mm exit pupil, so pretty bright liao) and star hopping around while learning the skies. You have tripod + head?
Have fun observing wherever you intend to observe!