The Gen3 is not a very big vehicle, as a matter of fact I can't fit my wife, lab, kid, and a load of camping for the weekend inside the truck. The rear cargo space is poorly utilized with the way the plastics are designed (although I love the 3rd row seat storage compartment for gear) which makes it difficult to pack to the roof, especially with a large dog. The pro's of the Gen3, particularly the 2003+, outweigh any cost savings over other models in my opinion. I also feel the gen3 is a sports car compared to the 80 series Land Cruiser it replaced, weight and size are subjective. For the uses the OP stated in his first post the 03+ sounds like the best vehicle for his needs especially if kids are in the future. I saw an 03 pop up for $2k locally so they are out there, I paid $5k for mine with 140k on the clock for reference. Be patient and wait for the right truck to come along. I think the biggest problem with the Montero lineup in general is the lack of support and parts for the vehicle, even from the dealer.
Edit:
After I made my post I was thinking about the $4k budget. You can probably buy a truck for that price but you also should plan on bringing any used vehicle up to date with repairs and such. Timing belt, leaking valve covers, brakes, fluids, tires, worn out suspension, etc is all going to add up fast especially if you have to pay a shop to do the work. Just food for thought.
If you are located anywhere near me feel free to come take my truck for a drive and see if it will work for your needs. Are there other platforms you are looking at?