Ok Scag gave his advice and now i will give mine. I am 20. I been around the block.
In this changing world, with the rising gas prices, i would buy the smallest truck that could tow the equipment you have now most efficently! You do not need a 3/4 ton pickup and a $2600 dollor dump insert at 16!!!! Get your supplies delivered!!! I do big hardscape project. All my stuff gets delivered, down to a yard of top soil!!
Once you spend 2600 on a insert, and take into consideration the extra time it takes to pick stuff up, the wear and tear and the truck, and your really bad gas mileage, it makes no sense to pick up your stuff.
If i was you i'd try to find a f150 with the inline 6 engine. They are bulletproof and run for ever. Run the f150 for a couple of years doing just lawns and mulch etc. Once you get out of school buy a bigger truck and than go into hardscaping etc.
Feel free to PM me with any questions.