Are you using the log 'books' or the individual pages that are added to binder books? Either way, just start a new one when the old one is used, starting with your next dive.
I started out with the PADI log books that held the training dives. As it got filled and I decided what information I wanted, I designed my own pages to be printed and used in a small 3-ring binder. At the start of each year, I remove last years pages and start with new pages. I have a large 4" thick binder that all the previous years pages go into.
I've only been asked for proof of diving experience one time and that was at the time of booking. The dive op acepted a faxed copy of the last the pages in my logbook. As has been mentioned, I don't take my logbook on a boat.
I still have some dives signed off. Students get a kick out of signing my logbook and anytime I dive with cyber-friends I get them to sign it but as a general rule, unless it's a training dive I do not get signatures for fun dives.
Good for you for planning to keep an accurate logbook. You'll be glad you did!