It looks like you can get a spanner wrench in the end of the cylinder, that's how you get welded ones opened. Def get a cheater lens, I'm only 41 and been using one for a couple years now, in tight spots I got to where i can't get my head far enough away to see it, it all just becomes a blur. And yes it's easier to learn when you're younger, and it does take time, but the more you do it the easier it is. Save scrap from your travels and jobs (random junk is often at different jobs you may do, inquiring about stuff laying around has scored me many great finds, and thankful people that i hauled stuff away for them), even the big box stores have steel pipe gas line, I've built plenty of stuff from that. If you can think of something to build and grab scrap for it or budget material, the next thing you know you've got what you wanted for a bunch less.
Make some tools for the mini, maybe a big log arch that you can use with the mini to move and load far more than the mini will pick, or a big log dolly like
@flushcut did, either of those would be as cheap as an old axle and some pipe or something, and would give you more material handling capabilities than you currently have, making you more profitable. I've most of my stuff for the tree business and around the house, and i build stuff all the time for work at work too, including a big weighted base for the core drill so i don't have to set an anchor on smaller floor holes. The more you use it the more you'll find yourself using it as a tool for a bunch more than you ever anticipated, and won't hesitate to whip up your own tools as needed, or use it in ways you didn't think of before, like cutting u joints to pull parts or work on stuff.