Clothing for triking

Thoreau suggested that one should beware of enterprises requiring new clothes. "If you have any enterprise before you, try it in your old clothes." He was warning against taking up sports or activities that involve purchase of new clothes. It has always struck me as foolish to buy all the gear before I am sure I enjoy the sport or occupation. You can cycle locally for example in street clothes. You don’t need to look like you are just about to climb the Cols de Vars, Izoard and Galibier in the Tour de France when you nip down the supermarket to buy a pint of milk. However sooner or later one wants to bite the bullet and buy specialised clothing.
We have just ordered a pair of recumbent trikes. We tried them last year and are looking forward to getting on the road this autumn. One of the less serious questions I am turning over in my mind is what clothing and equipment do we need to obtain when we start drifting round cycleways on three wheels?
Shoes are amongst most important items. You need to attach your feet to the pedals on a recumbent trike, because if your feet slip off the pedals and you get your legs caught between the frame and the ground while the trike is still moving, it can cause serious injuries. To quote an American friend: ‘"Leg Suck!" is what happens when you lose concentration for just an instant and fail to keep both feet firmly pressed against the pedals. It's only a few inches and a tiny fraction of a second before your heel touches the path and is immediately sucked back and under the cross-member of the trike frame. There are only two categories of recumbent trike riders: 1) those who ride clipped into their pedals and those who know their orthopaedic surgeon on a first name basis!’ (Thanks Stan!) You could also use toe clips with straps. Click pedal shoes cost 50 to 200 Euros in Germany. Toe clips are cheaper, but maybe less convenient in use. You can of course wear sandals, trainers (sneakers) or walking shoes, as you wish.
Most conventional cycling trousers and shirts have pockets at the back, which if these pockets are in use makes the clothing less than ideal for recumbent cycling. There don’t appear to be many European suppliers offering specialised triking clothing. Make sure you’ve got at least one zipped pocket as stuff can fall out onto the road. The only German company I have found is Icletta the ICE trike distributors (https://www.icletta.com/). The company sells some Bendit gear. ICE trikes offer a number of shirts and tops featuring the ICE logo: https://www.icetrikes.co/. Of course if you are riding a Hase delta trike or an AZUB, a KMX or a HPVelo machine you may not feel comfortable wearing gear from another manufacturer. The way around this problem is to buy neutral shirts from the afore mentioned Bendit. This American company manufactures a range of good looking cyclists’ shirts, shorts and trousers which is overjoyed ship its products worldwide (www.benditcycling.com). You will need to pay postage and customs duty. One complaint I have is that all of the company’s shirts are short sleeved and as a former skin cancer sufferer I would prefer longer sleeves. 
I have a strong suspicion that the running/jogging departments of sport stores could be a good place to start looking for triking gear, especially during the sales. One could pack valuables in what the Brits call a bum bag and our American cousins a fanny pack, if the running tights and shirts are without pockets. On our trip last year during a cold period in October we both wore running tights to keep our legs warm with 3/4 trousers over the top to give us pockets. This worked quite well. 
As for waterproofs it would be a good idea to avoid cycling jackets with a zipped rear pocket. Fortunately I have cycled in conventional walking jackets for some years now. Waterproof over trousers can be bought from outdoor shops. These are a good wheeze as otherwise your shorts or trousers get wet and the wetness diffuses up in to your neither regions.
I suspect a hi-viz waistcoat (vest) is not that useful on the trike. The seat will hide it from  traffic behind, but it might make you more visible to oncoming traffic.
OK the punch up question: Helmets. I notice that a lot of European trike drivers wear baseball caps or sun hats rather than a helmet (see “Tims trike trips” on YouTube as an example). I tended in the past not to wear a helmet when we were nipping down the supermarket, but did so when we were touring. What we are going to do when we start triking earnestly, I don’t know. One has less far to fall from a recumbent trike.
As we have enough conventional panniers to hang on the rack we won’t bother buying any new cool trike panniers. Many trikes have handlebar bags fitted on the side of the seat which let you have rapid access to camera and cheese sandwiches. However you need a support frame to carry it. Terracycle (https://t-cycle.com) and their German agents Icletta offer these as well as a wide range of gear.
Locks: I have a strong suspicion that we will carry our weight in locks when we are underway and try to only stop in Bed und Bike accommodation in Germany, where one is guaranteed lockable overnight bike storage (https://www.bettundbike.de/).