I did the same thing on my sons TT. We used the dicor adhesive. It had an inconsistent bond but maybe we did it wrong. Per all the recommendations and even Dicors recommendation we used the Dicor adhesive.
So this spring I had a small TT that I wanted to put an epdm liner on. I didn't want to use the dicor adhesive so I started researching epdm and found that it's normal to use contact adhesive. At that point I contacted Dicor and asked why they always recommend their adhesive and could I use contact cement. She said yes I could use it and the reason they dont recommend it is not because it will eat the liner, it's because when the two surfaces touch you better have it right. Well no doubt, that's how contact cement works and yes I could imagine people having a hard time with it. I had the liner situated and started at the center and glued about 2 feet back on both surfaces. I let it set up and carefully worked it back, then I repeated it with another 2 foot section until I reached the back of the TT. Then I worked toward the front. It came out smooth as a babies butt. It was perfect with not one bubble or spec in it.
So you have tpo and maybe they will say that contact cement is not compatible with it? Call Dicor and explain it in the context of how I described it and see what they say.
Contact cement is $10.00 a qt. Far cheaper.
His Rockwood 2008 had a small cut under the ac unit that was there from new. It also had a very small over cut when the razor knifed around the vents. The Dicor missed it by a quarter inch. You couldn't see it unless you got down there and tried to spread the tpo with both hands. It was not easy to see and easy to miss when touching up the dicor. His tpo was also felt backed and sucked water in and raised the plywood by the vent. Felt back gives it a nice cushion but when you get the smallest cut it sucks water in like a sponge.