That’s still a fairly worrisome amount of potential energy if a string snaps or a limb cracks or something. All told, better not to risk it.
That said, my crossbow is essentially a plastic flatbow stapped to a stock with a trigger mechanism. If you purchase the actual bow components, an experienced woodworker could probably run up a decent crossbow. (The non-obvious bits are that you need a clip to hold the bolt on the crossbow, and to use a thick string.)
Still probably better to buy one, that first time. And certainly with the arrows/bolts, you really don’t save much money by assembling them yourself. Go down to Quiverstock, get a dozen.
Poundage will be checked by the weapons check team with a bow scale (It’s basically a handheld string-powered scale, similar to those used in fishing, with a loop for the bowstring. They draw the bow, and take a reading.)
As for secondary weapons, I carry a pair of machetes (26") and a dagger (18"), so I have options. Other choices I have seen include single axe (36") or sword and buckler. I recommend against using anything 42" (or longer, because then it’s a two-handed weapon), because the length makes it more awkward to carry with you. The last thing you want is your sword tangled in your legs, or being slow to draw (yes, the extra length does make a difference.)
Target choice: In general, don’t go for the long shot. Larp arrows are slow, and your enemy has plenty of time to dodge or raise a shield. Prime battle range is at 20m or less, and even then, it helps to shoot targets who are not paying attention to you. Target priority is anything which your melee troops (you have some melee troops nearby, right? If not, you may want to be somewhere else quite soon) find difficult to deal with. Spears, other archers, mages. After that, whatever you can hit. If they’re wearing heavy, they will usually have failed to armour the knees and thighs, or if you’re feeling confident, hands or armpits. Don’t shoot for the head, and if you hit it accidentally, apologise.