With a lower first gear then you climb slower so the back wheel slips less.
I like Big Apple's because the rubber thicker on them so I have more life out of them before getting down to the carcass.
I get roughly double the wear from them versus other tyres I've tried.
On a trike you'll have a bigger speed range than on a bike, so a double or triple up front helps even with a Rohloff.
I'd aim for the first gear very close to the lowest recommended size then extend the range back upwards with more chainrings.
With a Rohloff then 2 gears is a x1.3 difference between chainrings and 3 is a x1.46 difference.
I find it easier with my Rohloff if I try and match the chainrings to these gaps.
For example a 38/56 front double will give you exactly 3 more gears, a 30/40/52 triple matches up with 4 more and a 26/38/50 triple will give you 5.
A 26/38/56 will give you 6 but you need to mod (extend) the front derailleur cage for it to work .....
If you have a 20" wheel with a 16t sprocket then a 38/56 double will work, 12.4"-96" and with a 26" wheel then the 30/40/52 triple also works.
You can always fine tune your gears by changing the back sprocket.
I run a 38/55 double simply by the fact that the chain with a 56t big ring catches on my chain guard when I shift chainrings.
A Schlumpf HSD matches up well with a Rohloff because it gives you an extra 7 gears.
But the extra drag in the overdrive mode means it's only really useful for going downhill fast.
I hit the overdrive mode on mine at 20 mph .....
How short do you want your shorts.
For very short tight shorts then look at swim wear .....
You can always wear longer compression type shorts under them.
Plus they dry fast.