Wait just a minute. You asked about getting a longer rod. You can buy a good Tenkara rod for $60-100, and a line is less than $20. I fail to see how that would ruled out based on price when you started this thread based on a question about buying a 9'6" or 10' fly rod, all of which start at more than $200. I'm not trying to talk you into Tenkara. It's no skin off my nose. But that response made no sense.

I didn't go into a lot of detail and you may not know who I am, but I am a Certified Adaptive Fly Fishing Practitioner and President of the Adaptive Fly Fishing Institute, Inc. I also am totally disabled with Mult Concussion Syndrome (mTBI), Bilateral Cervical Radiculopathy, Degenerative Disk Disease of the Spine, and am 3 weeks out of knee surgery for Osteomyelitis. That's what I meant when I said I'm familiar with what you're going through.

You've gotten a few good suggestions here from some other guys about things to try. Forget about the make/model fly line and different rods stuff for casting further. None of that makes a hill of beans difference. A longer rod will help you mend better, and different line types and tapers will mend differently. But none of that is going to make more than 5-10' difference in casting distance at the max unless you get into special purpose equipment. You casting technique is about 95% of what determines your casting distance. FYI, a perfect double haul added to a perfect casting stroke will only add a few feet of distance, too. This is another common misconception about the function of the haul in the cast. The poster who mentioned it got it right: it adds line speed. You'll need that from a seated position, and getting it by sharing the load between both hands is usually better than generating it all with one hand. But it isn't going to be a solution to the distance you lose by being confined to the bank. Tip: work on timing of a short haul vs. power in a longer haul. You'll get more mileage out of it from a seated casting posture.

To increase distance, you need to be thinking about things like: much longer rods and fixed lines for fishing small streams, spey for rivers and lakes, and integrated shooting head lines.

For things to aid you in relaxing your back waterside, there is a wide array of assistive devices to choose from. If you go on disability, some of this stuff will qualify as medical expenses for tax deduction purposes. There are even grants you may be able to apply for to pay for some things. If you become officially and permanently disabled, feel free to contact AFFI for assistance with finding resources along those lines.