I'm trying to lay up a 15'x120" end panel in qs red oak with grain running perpendicular to the long axis. The plan is to use Ultra-Cat PPR adhesive and clamp it in place with a melamine platen and clamping cauls. First attempt with PVA wrinkled badly. Works great with shop-sawn veneers, but this was too thin. Glue application was consistent, using a roller with a hopper. Any tips for flattening this out without a vacuum press setup?

I'm assuming that the 15' was a typo and the panel is 15" wide. You will need a lot of clamps and bars to distribute even pressure over the surfaces. What is the open time on your adhesive? You may have to refrigerate it to extend the time if necessary. PPR still has moisture content so expect some wrinkling of the veneer. The perpendicular grain layup exacerbates the wrinkling problem.
You will have to veneer the back in the same grain direction to avoid panel warping.
I have 6 x 4 beams made from particle core box sections that I lay on horses for glue ups. Level the beams so you don't end up with a twisted panel. Use multiple sheets as cauls to distribute clamp pressure more evenly. Put a sheet of poly vapour barrier between the veneer and caul so that you don't glue the whole thing together. I have bowed clamping bars about 2 x 1/2" in section with about 1/8" of deflection to ensure central pressure, not just at the ends. Use veneer tape on the end grain to give the veneer some stablity when you have to pull it out flat when laying it down.
Do dry runs to see how long it will take and that you have everything in place.
Good luck.

Ps I would be looking for a shop with a press and saving myself the stress.

Thank you for the advice Tom. Yes, 15" x 120"; still a glutton for punishment, just no death wish. It sounds like this would be a tough glue-up even for an experience veneer user, so I'm thinking your last piece is the wisest of all. Thanks again

By the time you buy more clamps, and make cauls, you could probably get a custom bag made and use a cheap venturi vacuum pump. If you want the panel to stay flat, you have to have a balance sheet on the back side.

Hey Rich--
I got to thinking about it, and after seeing how many new possibilities a vacuum press introduces, I took the plunge and ordered a smaller unit. They're more affordable that I had thought they would be actually. I'll post the results when I get something presentable put together. My theory is that with a more suitable glue, a softener to get the figure to lay down a little easier, the vacuum press, and more careful selection of the veneer itself, I should be able to produce an acceptable panel. Thanks for the input.

Forget the veneer softener. It is quartered veneer so it is more stable and the expansion is uniform and one direction. You shouldn't have a problem laying the veneer then quickly getting a melamine top sheet on before getting it into the bag.

So I bought a vac system, some ppr glue, and had a go. Overall, useable panels and a new skill in my bag of tricks. I tried veneering over 1/4” hardwood edges and got some lifting even after scuffing back to 60 grit. I’ll keep experimenting.

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Vacuum is the way to go I was dragged in and just finished 40 doors on plywood a few issues adding too much glue which causes problems . The pump I use was my CNC so the only expense was the bag these things flatten better than a press or any clamp setup I've seen .
Also, go see the guys their glue is the best PVA STAY AWAY they have bags that where I picked up my veneer quarter saw Saple

https://www.veneersupplies.com/