... on bikehike, I saved the route which came up as 163km with about 40ish waypoints when I try and view it on the GPS the screen has frozen.
Does that mean that you've added 40-ish 'coursepoints' and then saved it as a Route? Because the Route itself will save out from BikeHike with several hundred routepoints if its that sort of distance, regardless af any you may add. And that won't compute, in any GPS. The max is 250 routepoints at a time.
If however you've turned off 'Follow road (google map)' and just plotted a straight-lines Route with 40-ish points - that should be OK, and provided its =<50, should autoroute in the GPS, and with luck maybe even go the way you expected.
If it's a zoomed-out map on the GPS that seems to be freezing things, just zoom it in manually and quickly, several times. (left middle button)