building a 10 person table, raised rail with a permanent dealer spot and chip tray. I am wondering it needs to be longer than standard size.
A 4' x 8' oval table (outer rail dimensions) provides 24.68" of linear space per player when seating 10, or 22.44" if seating 11 people. Less than 22" per body is pushing the limits of being comfortable over very long periods of time. 24" per player is a good
minimum number for long-term comfort, imo.
For comparison, we routinely seat 9 final table tournament players plus dedicated dealer at 7-foot tables (84" x 42"), which provides 21.59" per person (until somebody busts out, then it's 23.99"). Works fine for nine total, but I certainly wouldn't want it to be any less for 10 bodies.
Working with the limitations of 4x8 plywood, you can design the base table to those dimensions, and cut out sectional rail pieces from another 4x8 sheet that, when combined together into one solid piece, actually extend an inch (or more) outside the circumference of the base table itself -- essentially making it larger than 4x8, and providing additional linear space for players (and without requiring expensive custom-cut lumber or extension/joining building techniques).
A 2" rail overhang (creating 100 x 52 overall dimension) would generate 23.58" of linear space each for 11 seats (ten players plus dealer) or 25.94" if seating ten, and probably how I'd handle your specific parameters. You can minimize the amount of space needed to be controlled by the dealer by a) incorporating a dealer station inboard recess in the table, and b) marking the betting line so that all chips placed into play are within the dealer's reach.
I'd also make the dealer tray an optional feature that can be swapped out for a flush table-surface plug for when you don't need/want the tray in place (or just go with an under-table drawer solution).