5,000 will get you most of what you want to do.
first thing buy a professional backpack blower and weedwacker, possibly a edger. second buy a couple of rakes, shovels, traps, wheelbarrows ect you don't need the best hand tools but a good pair is recommended. 2,000 should get you a used 48 hydro mower and a push mower. spend the rest on advertising in one shape or another. this will allow you to do basic install jobs, mulch as well as maintenance. don't spend half your money on a trailer that won't do the job. your Dakota is fine, it might take a little longer but it will do the job. towing the trailer with the dakota? possibly if you have the 5.2 v8 engine, up to 1 ton on the trailer with electric brakes.