I have tried homebrew outbackers, MP1, buddistick and a whole bunch of others for portable use and on my backpack, but tuning WAS NOT easy.
Quick tip on what I do - we all know that hand body capacitance detunes the antenna. Let's actually use detuning to help!
Coarse - move slider / coil tap and remove hands. Repeat for loudest noise.
Medium - At resonance, a coil is easily detuned by hand capacitance. Again move slider / taps up or down a turn or two, and with coil in between your hands, use a clapping motion without actually touching the coil. This will help your ears notice the difference in the loudness of the noise. The best resonance occurs when your hands are detuning the antenna at the farthest they are away from the coil. With slider-coils, I use a twisting motion rather than using a straight up and down motion to get very close.
Fine - adjust the whip. If you start out with the last section of the whip only extended half-way, this gives you a little leeway either direction.
Of course body capacitance detunes everything too, but usually this can be taken care of with the fine whip tune and walking back to the rig once or twice.
One reason manpacks or directly-attached antennas to the rig with very inefficient whips may seem to perform better than a tripod-mounted vertical located a short distance away from the um, picnic table, is that not enough attention has been paid to rf-choking the feedline at the feedpoint.
Unless you provide a decent amount of feedline choking, AND especially if your feedline runs along the ground, THAT common-mode of the shield's outer skin-depth becomes essentially a 1-wire on ground radial system, despite any other radials you may have elevated. Merely elevating your feedline 6 inches or so above ground with plastic beer coolers (or whatever) and watching your swr change drastically will help confirm this.
If your swr gets worse, you are actually heading in the right direction! Although this may put it out of the range of an internal tuner, now that the antenna is resonant, you can take care of higher swr's with shunt-coils (ie, 4 turns 1" diameter for 20m) across the feedpoint. Or of course use an external tuner, but this should be the LAST step. Antenna analyzers certainly help out, but if you use it to tune 1:1 and don't actually listen-for-resonance, you could end up with a very reactive low-swr. Your transmitter will love it, but you may not get out of the camping ground.
Ferrites or air-core coax loops can help, BUT the amount of turns depends on frequency. See this chart to help out, although personally I prefer ferrites or transformer rf-isolators:
Common-mode chokes
You may not need a manpack after all as long as that feedline is taken care of.