Hi ekps
Please do not give me a lesson on carpet cleaning just your opinion
First off , not the best way to endear yourself to proffesional carpet cleaners !.
second lets look at the problem you have .
1 you can get work
2 the rug doctor does a good job ,you think
3 the rug doctor is hard work
4 you have little money to re invest
solution keep working with the rug doctor until you can afford a portable with at least 100psi and twin vacs.
once you have this purchase a machine that will mechanical agitate buffer sebo or invirodri.
step 2 work hard again then purchase a machine that will produce 500 to 1000 psi and can be worked from a van and can auto fill auto dump and produce high heat at the right end .
step 3 work herd again
Moo then purchase a truckmout( a big thing in your van that makes a lot of noise and costs a lot )
Job DONE
Neil.
Ps Odd course might help
Ie How to win friends and influence people
Hope this has been helpful
Neil