Lance TTs have the spare in the tongue A-frame. I think there's another brand that does too. Not sure if you could just bolt one in or you'd need to do a bit of welding. You also need to remove the standard battery box supports. The battery(s) would have to be moved somewhere and then you be taking away the tongue weight you want to add. Warranty-wise, this may or may not work and I would confirm with the dealer. Could get rather costly too I would think unless you did most of the work yourself.
BAL makes a spare tire carrier that goes underneath called the hide-a-spare. It comes in 4 different versions depending on your type of frame. Available here on sale for $199 total
Hide-a-spare or here at reg. price for $160 total
Hide-a-spare (cost may vary depending on your ship to location)
You could mount the BAL carrier as far front as possible, just rear of the A-frame. I think this would be the better way to go and would be close to the amount of weight added by having the tire
in the A-frame. It's a simple bolt on too. You'd need to locate it so it doesn't conflict with the stabilizers. I'd like to install one if I can talk DW into it.
Some have gone to an auto wrecking yard and removed the spare tire carrier from under a pickup truck and adapted that. Do-able but not a simple bolt-in job.
Just what is your tongue wt. and GVW of the TT? The factory specs say dry hitch wt. is 739 lbs and dry wt. is 5676 lbs which works out to 13%. I would expect it to go up when fully loaded. It doesn't list GVWR but it should be 6701 lbs (CCC + dry weight). Not knowing the TT's actual weight, you want a minimum of 10% of the GVWR or 670 lbs, but the factory amount is above this.
How much additional weight have you added for DS's special needs? You'd have to add quite a bit to upset front - rear balance that much. And then I'd be questioning whether or not you've exceeded the GVWR, which you don't want to do.
People often say you can shift weight around by loading things differently. Personally, I just don't see how that can really be accomplished by any amount that will really make a difference. It's not like you can load all your food and supplies on your bed and then move them back into the kitchen when set up at the CG.