I am applicaiton developer too.
I once met a new company who really want to hire me, their system crash, and give me title manager and pretty good salary. But whatever I request, they can't let me remote work at home 3 days a week. Because, they already feel insecure about system crash, and new manager would take time to get familiar with team member and this application business system logic... so I understand it, and refuge this offer.
By your case, it is similar. You think you can remotely work because of 5yrs working on this system already. But your boss might think different way. It depends his style and how he thinks about this.
If you are very important technical source, he might compromise. You can try. Just you can sense your boss working style and what his best intestests. If he can find another guy, or himself can do most part of your job from technically and he won't worry about that transaction when you leave, he might not like your this idea.:)
