start with something large in terms of edge length then drop that value by half to tighten up as needed, so that looks like:
1st edge length to get the party started, 1.5 units, 2nd pass, drop to .75 units, evaluate with mesh wires off and input object hidden… render view works great for evaluating.
3rd pass, drop to .375, evaluate, etc… then start using finer adjustments as needed.
add a little smoothing and some poly optimization (or not)
but as you saw…going full whack from the start is a recipe for a crash or lockup as shrinkwrap is a big RAM hog.