I'll join those suggesting that this is probably due to a worn component/components somewhere rather than just a wheel alignment or tire pressures, altho it is possible that checking tread temps &/or pressures could help in the diagnosis. Have you tried to get a tread temperature reading after ryding for an hour or so?? One of those infra-red 'no-touch' thermometers should be up to the task, just so long as you do it as soon as you stop. Or you could look for a 4psi increase from your cold start tire pressures after an hour or so's ryding - more than 4psi suggests low cold staring pressures, less than 4psi suggests high cold starting pressures. If you only ever ryde for 30 mins or so, that'll do for either method, but doing either/both should help identify fairly quickly if 'low' tire pressures might be the culprit or contributing.
There again, I know your location says PA, but if you regularly ryde in 'hot' ambient temp conditions, on 'hot' surfaces, or load the front tires up a fair bit thru working the twisties hard or caning the brakes, that could also be part of if not all of your problem.... Or, it could be that at some stage in the life of those tires you (or a previous owner possibly?) did something for saaay at least 1000 miles or so that started that wear pattern - often, once a wear pattern is set into the tread, you can be unable to align it out or adjust pressures sufficiently to fix it!!
But I'd still guess there's gotta be a couple of worn ball joints, dud shocks, over-loaded springs, or loose wheel bearings in the mix somewhere.... Or maybe possibly there's an incorrect 'static ride height' setting or too little/much spring pre-loading that is throwing the camber setting out of whack as Merlot suggested earlier?? Do you have pre-load adjustable springs/shocks on your Spyder?? If so, check the loaded ride height & camber against BRP Specs for your model Spyder - IF you can get them; otherwise aim for zero camber with your Spyder loaded & you/your normal pillion passenger aboard.
Good Luck!
