Can I throttle my own connection?

Inserting a 10/100 link in the mix is not likely to have a demonstrative impact.  If it's upload that's saturating your utilization, a 100Mbps link would still be faster than the upload channel and not significantly slower enough than 500 to really matter.

On the consumer side, a router w/QoS is likely to be the most economical approach.

My weapon of choice however is pfSense.  The traffic shaper feature is highly tunable by source, destination, as well as schedules.  If you're technically proficient, adventurous, and have a spare PC of some sort with 2 or more Ethernet ports it's free to try.

Inserting a 10/100 link in the mix is not likely to have a demonstrative impact

Yea, I was thinking that after I typed it. pfSense is a great solution but one probably beyond the technical prowess of the OP. I have a Asus router and it has 3 kinds of QoS. You would want one that has a bandwidth limiter atleast.

Quality of Service (QoS) ensures bandwidth for prioritized tasks and applications.

• Adaptive QoS ensures inbound and outbound bandwidth on both wired and wireless connections for prioritized applications and tasks via pre-defined, drag-and-drop presets: gaming, media streaming, VoIP, web surfing and file transferring.
• Traditional QoS ensures inbound and outbound bandwidth on both wired and wireless connections for prioritized applications and tasks via manual user-defined parameters.
• Bandwidth Limiter lets you set limits on download and upload speeds.

The hogs are my Rokus. So streaming seems to be more than 40% of the total data consumption. I was hoping I could limit the bandwidth to those devices since most streaming services have a sort of rolling quality based on the connection speed. I'm not looking to change my streaming habits, but I'm also too cheap to pay such a crazy rip-off amount for more data allowance from Cox. I may try looking into what you advised about the switch since most of the data is from streaming. 

The hogs are my Rokus.

AFAIK Rokus only have 10/100Mb ethernet ports anyway, so I don't think a 10/100Mbps switch would throttle much. I believe bridging the gateway and using your own router is the best option.

I have been using the schedules for down time on my work computer. It works nicely. One of the features that I like about the gateway. I hear ya on the streaming. These UHD movies and shows are taxing. 

A 4K movie on netflix can use over 8gb an hr. so, an 90 minute movie, 12gb. 2 in a day, 24gigs of data, an you haven't even read your email! LOL:.