Seo has lots of different ways to look at.
First of all i advise you to use a sitemap creator.
https://vborg.vbsupport.ru/showthread.php?t=100435 this is a pretty good one. I am using this for a long time and i am pretty happy with the results.
Also you may choose to use a modrewrite hack. There was a free one at vb.org but also there is another one with license. I also advise you the licensed one because it has many features. I used to have 22k pages before i purchased vbseo and currently i have around 99k pages indexed by google and all the past url's have been droped.