Recommendations for testing speeds on a FTTH network

I work for an ISP that has a fairly decent size FTTH market. We currently have somewhere in the range of 25,000 customers. We only offer gigabit speeds for our customers, and have marketed ourselves as guaranteed 950+ megabit service. For 90% of our customers they could care less what their speeds are as long as netflix doesn't buffer, and things generally work. Unfortunately we always have those few customers who like to just run speed tests, or verify their service. (For reference we had one gentleman that purchased a brand new top of the line mac book pro specifically for running speed tests. No apps or anything was loaded to the computer. If he thought his speeds were bad he would boot up the mac and run a series over an hour or two. Then report to us how terrible our service was because he was only getting 800mg on his tests.)

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So to the problem at hand; right now our only way to verify if a customer is getting the speeds they are paying for is to run an ookla speed test to a dedicated server at our core. This keeps the traffic all on net. Unfortunately some of our markets are 100s of miles away from our core and have to hit several switches or routers before making it to the server. This tends to cause our latency to be up in the 10-15ms range. Adtran, our vendor for GPON equipment, has told us that latency above 10ms can cause issues with the TCP windowing and lowering the resulting speed test. On our MPLS network we have the ability to use test sets to test the circuit with out relying on a protocol like TCP to show bandwidth capability. Is there any offering of this type available for a GPON network? At the same time what is the best way to provide a customer an ability to test their bandwidth capability with out over complicating the process. We've discussed adding more Speedtest Servers in our network, but one of the concerns is we only have 2 exit points from our network. Would it be considered bad faith to have a speedtest server not actually at a point where the customer's traffic would be leaving the network?