weight of water too much?

My water heater is always full but I usually travel with the fresh water tank about 1/3 full. That's just me though. AFAIK, RVs are designed to travel with full tanks, and I sometimes do that. I do usually dump the grey and black tanks when I leave a campsite.

I have often traveled with the fresh water tank full.

We have often traveled with full water tank, since we were camping in sites with only electric hookups. Tank held the water just fine. Of course, water tanks - and the means that hold them to the trailer frames - were designed to hold the weight. It would be pretty silly if they weren't.

Congrats on owning a trailer. If mine couldn't haul full tanks without problems, I'd sell it.

My freshwater holding tank is inside the 5'vr under the sofa. Small too I think it's only 25gallons but I cant find any markings verifying that.

Travel with them full all the time to avoid having to fill up the tank when we arrive at the state parks that only have electric.

I've seen the pictures of some units when uncovered and the support system on some is minimal at best, but to my knowledge, they are all meant to be towed with water in the tank. I almost never tow without a full tank since we do State Parks a lot. I'm going to have a look at mine this spring for a venting issue but you can bet I'm checking the support too while I'm there. I'll add support if I think it's needed.

Can you? Yes. But why would you want to schlep all that extra weight around?
Most put in about a 1/3 of water for use for the toilet etc. while on the road. Fill the fresh water tank up when you get there.

I travel with my tanks full quite frequently. If I couldn't do that then I'd figure my camper was defective.
Many times where I'm going there isn't any water, hence the full tanks.

Yeah we take ours full all the time to races where there is no water once we get there. No problems and I feel it's built to withstand this normal use.