Mancavedweller, by what you say, you're over-qualified for the rental business. Stop goofing around and tackle some work that the guys who are always available for those last minute rentals aren't able to do. It doesn't matter if you're the best swimmer in the kiddie pool. You're too big for it, anyway. It's time to give the beach a try.
I'm not knocking the rental work. It's income and it counts. I know we have several members here who work on a day rate basis and do a fine job of it. But in your case, it should be filling in the gaps between your bread and butter jobs. Whether those jobs are in your shop or out on a job site is up to you.
CM- I had a GC who asked me to look at a job. He was all smiles and pats on the back and kept offering me cigarettes (I don't smoke) as he explained the job to me. I nodded and listened and for about 20-30 minutes we walked around the site and he was my bestest friend in the whole wide world. At the end he tells me that he only has a budget of 3,000 euros to do the job. I said okay, shook his hand and I left. A few weeks later, I saw him again and he said that he never received my estimate. I told him that I knew he only had 3,000 euros to do the job and that it wasn't going to be enough. I also told him that I knew he was being straight with me on his numbers and I couldn't put him in a position where he couldn't pay for the work- the job would have been fairly priced at 13,000 euros, but the dumb look on his face was priceless.