Father/son getting started

My 11 year old has now moved from Cub into Boy Scouts. The Troop (and our family) has only done car camping previously and I'd like to do some backpacking with him and hopefully get the others involved as well. I have no experience though – just like to hike when I have the rare opportunity.

Therefore, we have no real backpacking gear so I plan to get the very minimum now and work up to more as his interest continues. I plan to only do 1 or a max of 2 nights at a time until we both get some experience.

I figure we can get buy with renting packs from the Scout shop ($3/day) so I'm figuring the first thing we need is a tent. We have 2 small tents but neither will fit both of us and he doesn't like sleeping alone. Thus, I'm looking for something that will EASILY fit 2 adults. Despite the much heavier weight, I was looking at the Alps Mountaineering Orion 2. However, the Meramac model is nearly half the price though also a bit heavier, fiberglass poles and no vestibule. I assume the same for any big box 2-3 person tent. Or should I just bite the bullet now and get a true lightweight tent such as the Double Rainbow for more than twice the price?

I THINK the only other thing we would need is a stove, but I can put that off for a while as we'll just do 1 nighters to start and can manage with only dry meals. Our first one will be May 29-30 unless the weather sucks.

BTW, he's almost 4'11" and 115 lbs – a bit chunky but not athletic. I plan to keep HIS total pack weight < 20 lbs, preferably < 15 the first few times. That should be easy I'd think for only an overnight trip.

I'd appreciate any advice to make sure I'm not missing anything or if I need to clarify something.