I'm not trying to advertise any sort of product here, but I've used a mantis tiller in the past and it does very well at digging through hard clay soil. The soil will obviously have to be amended with some type of organic matter, and the deeper into the soil you get the better. Remember that these plants will want to be as big as possible, and the deeper the roots can go the larger the plant will be. When you're ready to amend your soil (I suggest waiting until fall to do this), do some heavy weeding beforehand. If you try to till the weeds under, they'll come back even bigger after the soil is amended. Anyways, in the fall, get as many bags of leaves as you can and dig them into your soil with the cultivator. In spring, you'll have some good soil for planting.

Go to STarbucks, Krystal, Waffle House, Cracker Barrel and ask them to save you coffee grounds and put a ton of coffee grounds in that soil after amending it with a top layer. The worms will come to the coffee grounds. There are basically three types of worms needed to irrigate the soil. If you do lots of coffee grounds after applying a top layer of soil and gypsum annually, you will see a definite improvement. I also used corn meal on mine which helped. Someone told me to use it for blackspot which is not worth the time it takes to put it out for blackspot but it did help with the coffee grounds and gypsum. We had to add a French drain on one side of the garden but subsequently we got the soil draining pretty good. The French drain is probably a breeding place for snakes or voles now. :)

I think I would prefer an axe of any size over a mattock so maybe you can borrow one before buying. My mattock would just bounce off of large roots. I have never seen root guard but the contractor said he wants to use as little as possible because it is expensive. It sells by the foot so must be at least a little flexible. The Hi-Lift jack is one used by off roaders and there will be many pictures of them on Google. In some off road situations, you would be really glad you brought one along and they have many uses in addition to jacking up vehicles. It would not be good for very many cars although I got my Camaro out of a rut in Wyoming many years ago. The alternative walk for help was not very appealing in my location at the time. My Hi-Lift is the four foot high model and has done everything I asked of it. There are some knock-offs offered by Harbor Freight and others but if buying one again, I would still go for the real thing. I finally gave away my large tiller after owning it for 30 years. It seldom got used after I bought my Mantis because my entire yard had been tilled deep. I would not hurry to buy a Mantis either because I doubt that they are suited to all situations. A wrecking bar is a bar of steel about six feet tall (approx) and about an inch or so in diameter. They are really useful sometimes. When I bought my house, we had a bed of Bird of Paradise plants and I liked them until my wife wanted to move them. After finally getting those things out of the ground, they went into the garbage. A neighbor offered me a giant Bird of Paradise once as long as I dug it up. I dug for a while and got nowhere so it is still in his yard. I don't want one that bad. Bamboo is also something that I would never put in my yard after removing all that were left to me by the previous owner of my house.

Some of the old stuff I took in the civil engineering soil mechanics courses are coming back now after thirty years. The suggestion given on digging the ditch deeper, assuming this is a "drainage ditch", and not a dugout, within your property would help during "normal drier times" in lowering the phreatic surface of the ground water within the soil (fancy old fashioned technical word that just means ground water level when not telescoping out into the open as the surface of a lake) . But during floods doubt it would be of much help as the water will still rise to and above the surface if your in the lowest spot and the ditch is not actually flowing, or is too small for the quantity of surface runoff and ground water discharge. You should also watch out for digging the ditch too deep with steep walls because it's sides can subside (fall in) from pore pressure dissipation if your soil is sandy or loamy. In the end though, the ditch needs to flow and be sized for the flow to get rid of it. I had minor "water problems" in this property compared to yours and it was caused by me making the gardens by building 12 to 18 inch high rose beds and cutting the surface runoff escape to the swale.. It took two 9 inch rectangular catchment basins (sewer traps) and about 100 feet of drainage tiles and ditching to prevent the surface water and eaves trough water from ponding against my garden beds at the two lowest spots. I cut off the escape to concrete swale (ditch) that runs across the back of my property. The biggest pain I had was not enough gradient (vertical distance from house to swale) to accommodate the 6 inch diameter weeping tile ... so for the last 20 feet through the garden I used perforated pipe to let it go into the soil and cut two holes though my retaining wall for the discharges into the swale. It would be interesting to see photos of the rest of the situation - I find it very interesting but can sympathize with how it sucks right now especially having dug those holes for a lot of roses. Hope you success in solving it. Good luck.