With the slide out battery trays, there is usually plenty of extra cable available (so if you have to cut two inches off the end, worse case, your battery tray just wont pull out as far before the cable slack is used up).
Two important points. IMO.One - all your terminals look like they need a good cleaning. I would take a photo of the cable connections (mark them as needed "+, -") then remove all the batteries and thoroughly clean the battery terminals, cable ends, batteries and tray with baking soda water mix and small wire brush.
Two - if you install a new battery cable terminal, cut back the cable insulation and
be sure the copper is clean. Usually the corrosion will work its way up the cable - so you need to have clean copper before installing the new end. Sometimes you have to cut off a a couple of inches to get to clean copper (so you need a set of cable cutters - like these
https://www.amazon.com/TEMCo-Wire-Cable-Cutter-Electrical/dp/B00HJWTBYS/ref=sr_1_4?keywords=battery+cable+cutter+0000&qid=1576595693&sr=8-4 ). Also, you only want to strip off enough insulation so the exposed copper will go down to the bottom of the new terminal and very little exposed copper is showing sticking out (exposing about an inch).
When I replace a terminal end, I clamp the new terminal end in vise grips so the open end is pointing up and set the vise grips down so I don't need to hold them (you need to have a flat surface within reach of the battery cable, so having all the batteries removed at this time makes it easier and you can set the vise grips on the base of tray), then I use a map/propane torch to heat up the terminal end and fill the cavity about 3/4 full of solder, then while its still molten, push the cable in until it seats. Remove heat, and hold the cable still for a minute while the solder cools. Then slip your heat shrink tubing over it.
Sorry if I 'm stating the very obvious to you.
The crimper tool is nice, but if you only make up cables once every ten years or so, it's hard to justify the price for a good crimper set (that does up to 0000 cable). The solder method is as good but requires more space to work with.