A high lift requires, as you found, proper mount points such as in the front or rear bumpers. In order to do that though, they must be aftermarket steel obviously or some other custom modification to a factory bumper like a steel slot into them directly attacehd to the actual bumper steel underneath.
Using on the side can work but as you found, it's tricky. I don't know what bars you have but mine have a wide offset 2" or bigger tube that would just barely work if you get the angle started correctly.
The big thing though is using on the best ground surface, vehicle angles, safety in general.
I have 2 other options that are with me if I'm towing because there's plenty of space and a trailer can be annoying to swap a wheel off too, especially if you loose 2 at the same time on a tandem on the same side....
I like to have with me the high lift but also these items:
1-simplest, specifically on a tandem trailer, ramps because you can tow it onto the ramp leaving the bad wheel hanging free.
2-a low shop floor jack. There are some in aluminum that still have a high load but are smaller and weigh a lot less than my two big steel ones. This can work very nicely under either a trailer axle which is very low on an enclosed low rider 7x12. Or, it will also tuck nicely, and safely, under the lower control arm on an LR4. Now, ideally you plan ahead and have a nice interface material between the jack head and the frame parts.
The low, long arm floor jack is nice though because you can get it anywhere under the axles while safely using the long lever arm out on the side. It's also a wide base so in softer ground it should stay put. Though you could put under it a bridging ladder or a base plate like the one made for the high lift.
3-Bushranger X jack, which is a big tough air bag. I've never needed to use mine but it's not too heavy and will actually tuck away pretty well.
With any of the above, you can augment their functional limitations by having a couple other items along that are useful for various other purposes too. I like anything I bring to have at least 2 uses, ideally 3 or more
For instance in your situation, something to put between the high lift bar and the vehicle body ? How about a bridging ladder standing up between it and body with a towel against the paint. Or, the same item under it's foot if in snow or sand or mud. As 2000 lbs goes into its base, you don't want it starting to shift!
Same waffle board or bridging ladder could go under a low floor jack to increase it's starting height, and provide solid support.
I have these cool 3 section folding wheel chocks that are hinged to allow a triangle in chock form, unfold into long flat traction device, or zig zag fold into 4" thick high lift base, or to go under a wheel when roof camping to level the vehicle.
I would actually resort to all of the other ideas before hauling out the high lift and trying to use it to lift the lr3/4 so high enough to pull that suspension up. Frankly, the high lift is cool, but for most normal situations, there's a quicker and safer way to lift one wheel for changing.
These but no amount of googling is bringing up any current source or even web photos of it in use! :
http://www.roverparts.com/Instructions/T_M_ChockTracks_TR26.cfm
