If you pose it so the spear is resting against the base that can help add some strength, especially if you pin all three contact points (spear and two legs) to the base.
In my experience glass-headed pins are much stronger and more rigid than normal tailor pins or paperclips (or comparably thin brass rod), so you can probably get away with using glass-headed pins rather than brass rod or something - and since the pins are very thin at around 0.8mm it can be easier to drill the channels for them, making it less of a big job.
(BTW locally I generally find two sizes of glass-headed pins: the larger ones are 0.8mm in diameter and are much stronger than the smaller 0.6mm diameter ones).
On possible option of course is to replace the legs with more robust ones from a different light jack.
I don't have mm sized bits. not sure what the equivalent is. Mostly I use a size 58 for paperclips IIRC
You can get a set of drill bits of various sizes (usually something like 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.5 mm) quite easily online, I find the smaller sizes very helpful for pinning small parts (NYSS!) in conjunction with the smaller sized tailor pins.
I feel like this thread is a perfect encapsulation of the merc boards. As far as the buccaneer goes, I haven't had much trouble, but I kitbashed mine out of a cygnar light chassis and a net bit from a mini from another game. I've been thinking about making more since I recently got some extra net bits from the Devil Dogs unit, but I can't think of a list I want to run with multiple buccaneers.